OutboxItem

Collab

CollabFulfillsInvite
    collab CollabId

    UniqueCollabFulfillsInvite collab

CollabInviterLocal
    collab CollabId
    collabNew CollabFulfillsInviteId
    invite OutboxItemId

    UniqueCollabInviterLocal       collab
    UniqueCollabInviterLocalInvite invite