Whatever you do, do it quickly. If your buyers both got mortgages in March, they'll have six months, rates rises in the interim (95% LTV on a 25 year term, 2 year fixed rate)
31st March 5.89%
9th June 6.36%
14th July 7.08%*
*this rate will already include an anticipated 0.5% rise on 03/08 for the majority of lenders, sometimes after the announcement they even drop a little bit
Now, the thing is, the lenders seem to be trying to keep rates as low as possible for FTBs as they possibly can (it's those with equity who keep getting slayed) but I still think we're going to have two more 0.5% BoE base rate rises (3rd August and 21st September) and I think for the rest of the year they'll probably be 0.25% rises, because the Govt cannot get inflation under control. The BoE Monetary Committee meet every six weeks.
That won't put rates up by an entire 1%, but maybe 75% of that. In fact it won't take that long, if they put it up 0.5% in August, lenders will start putting rates up three weeks before 21st September (I have been closely watching, it's a definitive pattern).
If we see rates increase to 7.83% come 31st August, that's a massive difference in people's bank accounts. On a 100k mortgage it's the difference of a payment of £722 per month versus the £605 it would have cost them on March's rates.
Maybe they could extend by 1 month until October, but goodness only knows what rates will look like by them, and if your buyers could even still afford them.
Sources of all these mortgage rates btw are from Mortgage Strategy who get their rates from Money Facts (I archive all their emails).
If you have to move and move quickly, I would suggest the following:
Look for three bed garden flats instead of houses
Look in areas further away from schools and shops and good transport links
Look in towns you wouldn't usually look at; heck, look at different counties
Start making other concessions; lose three doubles to two doubles and a single, lose a big garden you could play football in to one that's big enough to sit out in for now; lose a decent sized family kitchen to a smaller one that doesn't even have a dishwasher.
Specifically prioritise viewing properties that are either a) very clearly vacant or b) state they have no onward chain. Be careful with b), make sure that no onward chain is actually real - it's no good if they're waiting for a house to be built that could be finished late, you need someone ideally who has actually bought another home or has already arranged a rental.
Get in touch with EAs and tell them you want to be the first phone call they make when a property comes up with a motivated seller who can move quickly.
Sorry if the above is a bit scary. Is it better to be prepared and informed or to dig your head in the sand? In this market, I don't really know.