silent partner
a party to
accessory
accompanier
accompanist
accompanyist
accomplice
accumulate
ace
act in concert
act together
affiliate
agglomerate
aggregate
aggroup
ally
alter ego
amalgamate
amass
amigo
assemble
assistant
associate
attendant
band
band together
batch
be in cahoots
be in league
bedfellow
bedmate
better half
birthmate
bosom buddy
bring together
buddy
bulk
bunch
bunch together
bunch up
bunkie
bunkmate
butty
cabal
camarade
cavalier
cement a union
centralize
chamberfellow
partnership
act
furnish
move
provide
render
supply
partnered
partnering
partners
agent
colleague
companion
customer
employee
friend
investor
lawyer
lover
manager
member
organization
owner
player
teacher
Gartner
opponent