A huge thank you to everyone who has contributed with helpful replies (but don't you just wonder what a deleted message said? I'd love to know! Could an alternative milk dialogue really infuriate?!
Schnackie, I won't say that I doing it with a completely good heart but it's one of those 'right thing to do' situations!
Tree71, you are right, I have not actually asked, however when eating out with her she checks menus beforehand and is very particular about what she is served so I think she probably... won't be able to tolerate normal dairy milk. I will double-check though!
Mildmanneredgran, you'll be very welcome. I had no idea about oestrogen in soya milk, so thank you for that tip. Of course, I can't vouch for the baking with an altered milk!
Yorki, invite sent. I am sure.... I will cope.
grandtanteJE65, good point about the butter but I had thought of that. I have several recipes where sunflower (sometimes rapeseed) oil is used instead. Surprisingly, the cakes turn out to be really moist and not at all oily but thanks for the warning.