I think this might involve some extra functionality:
1. Handling multiple contacts individually. Like current functionality with added possibility to link multiple contacts, select one from the linked contacts, and handle it like the current linked contact is handled (send a message to the contact etc.)
2. Handling contacts as groups: Selecting more than one linked contact and do something to all selected contacts (send a message to all selected contacts...)
I would be really happy even with only the first functionality. I guess the second functionality would also be welcome by many users. All this is possibly not quite trivial to implement while keeping the UI simple and intuitive.
I think this might involve some extra functionality:
1. Handling multiple contacts individually. Like current functionality with added possibility to link multiple contacts, select one from the linked contacts, and handle it like the current linked contact is handled (send a message to the contact etc.)
2. Handling contacts as groups: Selecting more than one linked contact and do something to all selected contacts (send a message to all selected contacts...)
I would be really happy even with only the first functionality. I guess the second functionality would also be welcome by many users. All this is possibly not quite trivial to implement while keeping the UI simple and intuitive.