Brian wrote:

Yes~~ there is a very narrow band of compatibility. Apples will only
graft on to apple rootstocks etc.. Pears on pear or Quince. They can be of
any varieties. Quite a few of the 'plum' family will take on the plum type
rootstock so that plum, peach and nectarine would be possible on one
rootstock~~ but would be better alone..

Ahhh. I didn't realise the choice of rootstock was so restricted.

James