yes, like this.
to be correct, I meant a function that adds standart wp meta to post AND saves mf relationship, because if I use mf, all add/upd/del meta operations should respect mf relationship.
add_post_meta_mf(post_type,field_name,value, group_index*,field_index*)
or maybe you could hook add/upd/del meta operations, and update mf relationship from here (both for admin-panel updates and for user-called add_post_meta), without adding new functionality, just using existing for both cases.