Hi Snowdrift,
Sorry to hear about your problems!
Organising a mortgage with your sister will lead IMO to all sorts of trouble, particularly if relations are not good to begin with. Also if she cannot secure a mortage now from a bank, what makes you think you'll ever get the full repayments for her? What happens if the euro collapses? What happens if interest rates rocket and your own mortgage repayments shoot up leaving her a handy low rate? To many complications for me.
As regards trying to play it cute and hold out for when property picks up in value - the phrase "A bird in the hand" comes to mind. I'd be taking the money and running. By all means re-invest in property if you wish, but then you get to decide what/where to buy and to whom you rent it to.
If your sister does come up with the readies to buy your half, then unless ye both get it right (unlikely) then one of you will lose out on the price agreed vs what the house would fetch on the open market. It sounds to me, based on your earlier posts, that you'd be happy with a lesser amount. This sounds OK until you realise that you are giving your sister money belonging to you. Should property prices fall further then be prepared for endless moaning about how you fleeced her. If prices rise, things will be quiet.
If your sister plays hardball and doesn't want to sell then I would advise her that you'll be moving into the house also (spend a few weekends in a row there and bring some mates).
I would also remind your sister that any legal fees would be settled from the proceeds and that in these times there are plenty solicitors looking for work
Finally, I would push selling the house as the
only option if I were in your situation.
Firefly.