Question:

Can a user's delegate log in as another user whose access is delegated to the user in PromoMats?

Answer:

No. If User A delegates access to User B and User B delegates his or her own account to User C, User C cannot access User A's account.

When User B is trying delegating his or her own account to User C or any other users, a warning appears reminding the user of this:

However, delegate user B can modify A‘s Delegated Access settings in order to re-delegate the account to C.

Related Documentation:

Vault Help Documentation: N/A