Assigning vendor at maintenance item level

Hi team,

If I assign a vendor at technical object level, how that vendor will be passed on to the maintenance item level?

In user-exit IPRM0003 if I have a custom field partner to maintenance item then will the vendor passed at technical object level will be passed on to partner field at the maintenance item level?

If it is passed then the can we use user-exit EXIT_SAPLCOIH_030 to enter the vendor data to work orders generated from IP10/30?