Basic information about conditionals here: https://www.ef.com/ca/english-resources/english-grammar/conditional/ Type 3 - hypothetical past If your late father HAD ATTENDED your wedding YESTERDAY, he WOULD HAVE BEEN very proud. If your late father HAD BEEN ALIVE and HAD ATTENDED your wedding YESTERDAY, he WOULD HAVE BEEN very proud. Type 2 - hypothetical present/future If your late father ATTENDED your wedding TOMORROW, he WOULD BE very proud. If your late father WERE ALIVE and ATTENDED your wedding TOMORROW, he WOULD BE very proud.

'Had attended' (past perfect tense) is a completed action. The future hasn't happened yet.