Have you looked in local tack shops for people offering help? I have seen quite a few lately whereas in previous years I have struggled to find anyone. The most success I had was visiting other local yards and asking if anyone would be able to pop mine in as they go past to do theirs, and I've had some really helpful teenagers who have happy to put mine in at 4 for me. They appreciate a bit of cash and as they were going past anyway its not too much hassle for them. I met a lovely local horse owner this way and we have helped each other out ever since.
I also saw a couple of ads asking if anyone needed help over the winter because people were missing doing horse work after having to give theirs up! So I guess they aren't expecting too much payment in return, just missing being around a yard. I think its worth having an ask around for some help before doing anything too drastic like changing yards (or pts!!!)
Not ALL horses can make the transition to living out happily. I have had a WB x who did brilliantly on it and I have a 24 year TB x cob who will not. Believe me, I could really REALLY do with having her live out from a financial view. She could stay on my yard, they feed the grass liveries x 2 a day and check/change rugs so it would suit ME brilliantly. Unfortunately, said mare is also a real diva and stresses wildly if left out. I have tried, I gave in. If anyone has any bright ideas on how to transition her, I would be very grateful. Oh and she is blooming picky about who she goes out with which doesn't help much either. As for OP, I would not split your 2 up. It honestly takes up so much time trying to go between 2 yards. Better off to have them together and see if you can chuck the younger out. By all means try the oldie but be prepared in case it doesn't work.
And another one who didnt get the whole PTS when OP never said her oldie was in poor health. My 24 year old is still hacking and looks considerably younger.
Thanks everyone. I'm certainly not about to PTS a horse that I have had for 20 years because I am busy, when it is healthy, happy and well. Said horse can be a diva, maybe it is the unknown htat I fear
I agree, if you can go to other yard with help then why Pts, but if their welfare starts to suffer because you do not have the time the you can Pts. You have that choice. Good luck