First one: With actual aproach
.- step1: include new many2one link to "everything" object.
.- step2: use the actual many2one as "partner" to make order or invoice and second many2one as "contact" (informative field)
Second one: With older aproach
.- Include many2one link to contact object (domain addresses of that partner, or related contact field partner_id)
.- Let the proccess as they were.
I see 2 possible solutions:
First one: With actual aproach
.- step1: include new many2one link to "everything" object.
.- step2: use the actual many2one as "partner" to make order or invoice and second many2one as "contact" (informative field)
Second one: With older aproach
.- Include many2one link to contact object (domain addresses of that partner, or related contact field partner_id)
.- Let the proccess as they were.