Question Author
Good question about the sellers moving out and renting from them, it was something i had thought about myself. Sadly, the sellers hold all the cards, so there is no reason that they would. Having exchanged contracts (which she had no choice about), she has no leverage, i.e. dropping out of the sale.
Also, it's one of these weird part exchange deals, so I am under the impression that the house is now actually owned by the builders, I know the conveyencer is dealing with the builder's solicitors, rather than a solicitor employed by the actually house seller. New builds are a nightmare, the conveyencer who is our daughter in law, hates them with a passion as there are so many complications.
I think if my grand-daughter had been aware of all the things that could go wrong she might have though twice. But the house is perfect, both in size and location and a really good price. Plus, when she made the offer, she was told that the house was ready to have its roof put on, and would be ready in June, July at the latest. Sinc then, of course, coronovirus issues have been a thing, which the builders have agreed.
The people who are putting the most complication in place is the bank. You would have thought that they would be more aware, and sympathetic with coronavirus issues, and they have been, but will not even consider the extension until there is not enough time to re-apply should they decline.
We have a house that is worth £220,000 and I am even considering taking out a short term secured loan for the amount they need should the new mortgage application, if that is what has to be done, is delayed. This is something I wouldn't have a clue to start on, so back to some research as a back up I guess