Sell/buy simultaneously or not?

[BorgQueen]

This is for my DD. She’s going to have to sell her home of only 4 years due to her partner leaving her and my DgC. She can’t afford to buy him out / take on the extra mortgage, it’s a big 4 bed detached very near a good primary school so should sell fairly easily.
She’s looking at putting it on the market in May/June.
She will have equity and can afford to buy a smaller house on her own.

I’ve said it might be best for her to rent for a while after selling in order to find the right house rather than rushing to find somewhere plus the stress of trying to sell and buy / risk of things collapsing but I’m also wary of her signing a 6 month lease then finding somewhere right away.
They could stay here with us short term but we don’t have a lot of room and she’d have to then pay for storage.

I’ve since found out that she can potentially split/ port the current mortgage and by doing so, the ERC will be a LOT lower by at least £5k ( currently £10k as they only fixed last year) so there would be more equity, she has more as she put 2/3 of the deposit in.

Not sure if conveyancing for sale and purchase together might be cheaper than doing it separately too?
Of course it all hinges on actually finding somewhere suitable to buy, it’s quite a narrow area - still close to school but also within 15 mins of me as I do most school runs - there isn’t much around at the moment, maybe 2 or 3 houses that are in good condition and don’t need major renovations and a hell of a lot of Sold STC.

Are there any pros/ cons I haven’t considered with both aporoaches?

Pretty sure sale and purchase conveyancing is the same however she does it. I'm trying to do both at the same time, but both are priced separately as standalone services - and lots of costs are about searches etc which will never change.

How long does she have left on her mortgage? I considered porting mine, but i only had 7 years left on it and would have had to keep paying it back over 7 years. By sucking up the redemption fee (In my case is only £1k or so) I could remortgage over a longer time period and keep my overall monthly payments roughly the same but for a bigger mortgage and a better house. Obviously any decisions there depend loads on debt appetite etc because a longer payback period means you pay more overall, but I guess in her current situation, keeping the monthly payments manageable on a single salary might be an important consideration.

Saving costs on the ERC is a big incentive to do it all at once.

Also I think there's a lot to be said for getting all of the stress out of the way at once. If she decides to rent for 6 months, it could be close to a year before she is finally settled. And it's always possible that she finds something quickly where the seller is very motivated. I've read that about 1 in 3 house sales are falling through, so some of those Sold STC houses could end up back on the market. In 6 months time, there may be less on the market as lots of people prefer to move over the summer.

If she does sell quickly, could she use your place as a fall back option, so that she can continue with her purchase if that's moving more slowly for some reason? If it's only for a couple of months, the lack of space at yours won't be such an issue.

Perhaps the best thing is to look at what's currently available and see if any of them tick all the boxes.

Yes I would try and tie in. It doesn’t make any difference to the conveyancing fees if you do it separately or tie in.

21 years left on the joint mortgage, 4 years of the fix left : £220k left and she will need to split and port around £150-160k ( she will have £50kish equity but won’t want to use every penny as a deposit, she has zero savings, despite earning a decent amount. It’s going to come as a shock going from a £100k household to half that and being responsible for everything.

A 3 bed semi is £180-£200k+ around here.
He’s agreed to foot the ERC and selling fees but who knows if he’ll stick to it, he’ll end up with £25-30k at best.

She could move in with us if there was a short delay on her purchase but if it fell through it would be hard for them to stay here for more than a few weeks, we’re further away from her work and the traffic is hellish as we’re separated by a major road. I go to hers at 7am to do the school run, half an hour later triples my journey time, it would likely take her an hour to get to work rather than 20 mins.
Taking my DgC to school from mine would also be a nightmare, we’d have to leave at 8.15 if not before. At the moment we leave her house at 8.45 for the 3 minute stroll to school.

I know a couple of people who when selling intended to do the selling and purchasing separately for ease but they then managed to find a house and did it all stimutainously.