for not wanting my sister to volunteer to help at my dd's Brownie pack?

I live with my family and it sounds odd but it is an uphill struggle to 'parent' my daughter myself. I work full-time and so my Mum collects from her school- fair enough. My sister works part time and takes her on the days she doesn't work. She began to go in to school read with the children (with my dd's class) but when my dd began Rainbows, it fell on a day when she didn't work. So she took her when I wasn't home from work in time. Pretty soon, I was home in time but too late to take her -they'd already gone. I already struggle to 'be allowed' to put my dd to bed since my sister often gets there first and has been known to over-rule me when I insist on things like teeth-cleaning after a bedtime snack: "milk is like teeth so you don't need to clean them again afterwards" being a typical comment. When my dd began Brownies, I was overjoyed it was on a day when my sister worked so was unable to take her even if she'd tried. I still can't take her but I can pick her up so I get a bit of "Mummy-time" and get to mingle with dd's friends' mums. So I get home last night only to be told smugly that my sister had volunteered to help at the brownie pack! I may be feeling mean but why has she got to go to that pack?? Why not another one if she wants to help out - I know that there is a shortage of Brownie/guide leaders?

There seems to be no consideration that I want to take my dd to or collect her from stuff - if we're on our way out of the door, my sister wishes herself onto us and it's hard to get her t0 see that sometimes, just sometimes, no offence but she isn't welcome since I want it to be just us. I banned her from coming out with us the other week to the cinema since I wanted some time with my dd alone - in a crowded cinema! and I've been paying for it ever since with snide comments like 'oh, we're not good enough for you now you are with xxx (my bf)'. We live with my family so it's not really an orthodox family situation - my dd's father left me when I was pg with her so I moved home - but why can't my sister get on with her life instead of "taking over" my dd like this? Even if I insist on meeting my dd from Brownies now, my sister will have been there and there'll be more 'in-jokes' between her and my dd. I wonder sometimes what my dd makes of it all. I can't afford to move out since I'm repaying student debts and any talks to Mum about my sister butting out just get the response 'oh she likes to help out' not realising that 'helping out' has become 'taking over'. She even turned up to the birth - I'd asked Mum to come and my sister was with her! So she saw her being born. Talks with Mum seem to be doomed anyway since she has always favoured my sister - subconsciously or consciously - and my sister had ovarian cancer 6 years so had to have a hysterectomy and can see no wrong in what she does. She tells me to mroe grateful but at the moment I feel like I was a surrogate mum for my sister and should go away now!! She has no kids herself. I feel sorry for her over that but at the same time, it's not my fault. I'm so angry now. Either she really wants to help and has no idea how much she's pissing me off (unlikely) or she is doing it on purpose to tweak my chain. Any comments to her about butting out just get teenagery-style reamarks about her being better than me since she didn't get pg out of wedlock ner ner de ner - which is pretty hard to take from a 43 year old.

Sorry rather long rant. AIBU??