To the partners you dislike: how about giving them an actual gift then you can spend as much (or little) as you like and add an accompanying note 'I saw this and thought of you'.
for me it depends on the cash flow - and I tell them...
also depends on age - if they 6 ( no not mental age you naughty boy! mentally they will be always be stuck in single figures) then 5/- will do for a standard handout, with the injunction - "spend it on sweeties!"
Exactly the same to all children, exactly the same, but, possibly a smaller amount than to children, to all partners, exactly the same to all grandchildren. I strive for parity!
To the partners you dislike: how about giving them an actual gift then you can spend as much (or little) as you like and add an accompanying note 'I saw this and thought of you'.