I could give you a long explanation about the issues you would run into, but I let me just say that for any practical purpose this is not possible.
The non-UI way to do this is to decide beforehand which healer wards and which healers HoTs or reactives, cure and debuff. This is because even if you had the big ward icon in the UI, there is nothing to tell you that it will still be there once you finished casting your own group ward 5 seconds later.
If you want to set up a heal chain, use macros to announce casting to a custom healer channel or /tell the other healers directly.
And before you ask: We can't display remaining ward amounts either.
