To not want to look after my sisters 4 cats?

I would just say, "I hope you're not expecting me to look after four cats" - if you say you're away in May, she'll think she can go away at another time and you'll be OK to catsit.

Interested in your reply about her driving you. Some families are very into give and take. If your contribution is cat sitting in return for a convenient taxi service, that actually sounds pretty fair. If you cut off what you are giving, you could find she is less into her giving ( lifts). Unless it’s like two lifts a year, I would think of the impact of this being withdrawn ( or less available).

Nah fuck that, it’s not like cats are even remotely grateful that you do all that fussy shit for them! Just tell your sister it is too much.

I love cats, but even I couldn't be bothered with all the fussing. I agree with others, say something has come up or you've developed an allergy.
YANBU

This. And if your children had double the amount of kids with no prior warning or discussion and expected you to look after them, you'd likely be overwhelmed.

OP be honest with her in a calm manner and do it sooner rather than later so that she has plenty of notice. If she doesn't like it, that's on her. The cats are her responsibility and she should have fully planned for this before taking on the responsibility.

I have a family member who house sits and looks after the resident animals. There’s a web site for it and the various sitters have ratings from the house owners. So although it’s a bit weird having a total stranger in the house, you have reviews to read through so you get an idea of what they are like. They don’t get paid either as they’re having free accommodation. And of course there’s conversations beforehand with potential sitters. She should look into that as a solution.

YANBU

if you don’t want to let her down for May I would tell her you can still look after the original 2 cats but she needs to put the two new ones in a cattery - that will at least save her money.

We are good friends with our NDN and they have teen girls who we pay to pop round and feed and check on our cat when we are away. And I am a crazy cat lady! She is my baby but I wouldn’t be constantly checking up on them and making demands. I am just grateful she is looked after by someone who cares about and knows her.

Given that she helps you out with lifts etc I would try and find a compromise personally.

Just tell her you are happy to sleep at hers but you will be busy during the day so won’t be able to pander to their individual whims and if that is not suitable she needs to sort out an alternative . Turn the tracker app off .

I have four cats with different 'requirements' in terms of feeding, health issues, and going out or not, and I would never in a million years expect a relative or even a paid cat sitter to stay and look after them. When we go away they go to a cattery. It's not their favourite thing but they can suck it up for a week.

So I'm effectively in your sister's position yet I don't think you are being unreasonable at all.

Just read an update you posted where you mentioned that if you leave the house your sister will text you asking when you’re going to return for the cats and honestly I think she’s being cheeky.

She doesn’t pay you, does she at least help you out in return or give you a thank you gift?

Without sounding nasty you are an adult and have your own life, I don’t know if you work or have DC but I’d say no going forward. If you really want to do May as it’s already agreed, do that then no more

She sounds like an entitled madam. Especially this

when she’s away she will message me if she can see I’m not at her house asking when I’ll be back for the cats etc it’s just exhausting

I would be saying that the above cannot happen, for starters, if you do agree to cat sit again. But, to be honest, with four cats it might be time for her to look into getting someone else in.

I love animals but, frankly, if your sister is so particular and concerned about her cats maybe she should stay home and look after them herself!

OP just tell your sister that 4 cats are too much for you to look after so she needs to be thinking about a cat sitter for her holiday in May. If you don’t speak up she may even get more.

Of course she can say no. We look after our grandchildren all the time but we have told our children we will never do pets. Fortunately they don’t have any.

Do you have to go to work as well during this time?

If it's only once a year, why not do it, but only if you think you can manage.

YANBU.

A SiL often has several cats, a couple of rescues besides the ‘permanent’ residents, some of which invariably need a particular food, medication, etc.
So if she and Dbro are going away, she employs a live-in pet sitter.

OTOH a dd has 4 cats, but none with ‘special needs’, so just popping in to feed twice a day seems to be fine for the teen neighbour who is paid pretty well to do it.

I would probably be upfront and just say that your happy to look after the two cats as promised but it’s a lot of work and you can’t look after the other two. She’ll either need to find someone else to cover or put the two new cats in a chattery for the time she’s away. Not unreasonable. It’s she gets funny then just remind her your doing her a favour!

I'm a huge cat fan but she's taking the piss. I have a thread at the moment in chat about a friend who has booked a month long holiday and is only with her latest boyfriend because he said he'd look after her dogs and cats. It's made me reconsider the friendship because she's become a user. Make plans for your pets before you book.
Tell your sister no, or yes but you can't do the food requests. Or yes but you're charging cat sitting fees.

“she will message me if she can see I’m not at her house asking when I’ll be back for the cats etc it’s just exhausting”

ditch that app too!
What nonsense 🤦‍♀️

Just say “no, thanks for asking me but I’m not able to do this anymore”.

When I started reading your post, I thought four cats wouldn't be much harder than two cats but then you detailed the 'rules' and I'd be stressed silly that I'd get something wrong!
I pop in to my DB's two cats twice a day when they're away and that's enough!
I agree with the pp who said to ask your sister if the two new additions will have special requirements too and just be clear that it's a lot of responsibility for you.
Does she give you anything as thanks for this big ask (even with the two cats)?

My initial response on starting to read your post was going to be YABU - I have 4 (used to be 6) cats. I don't think there's much difference between looking after 1 or 6 cats tbh BUT then I read that she Haa rules for each one 🫠. Nope. What a PITA. If one cat has a sensitive tummy, all cats get the sensitive food etc. Talk about making life difficult for yourself.

If she can afford to go on holiday, she can afford microchip cat feeders. When someone is doing a massive favour (which caring for pets is), the owner has a responsibility to make it as easy as possible!

Mind, a lot of people are like this with grandparents who do full time childcare - they keep popping out babies in the fill assumption their mum will continue to look after them (for free)!

Unless she's doing things which genuinely help you out in return, it's time to have the conversation that you don't want to be default cat carer. And please put a stop to her tracking your life360 and nagging you if you go out for too long - she's in serious cheeky fucker territory here and you need to remind her that you do have your own life and it isn't secondary to her or her cats!