I would take the $500 upfront and just log in to Squarespace or whatever website building service there is, do a simple design, tell him he needs to pay this subscription, argue with him and dad why there must be monthly or annual fees and they could have done this themselves for cheaper, whichever way they chose to pay the subscription or not I still get $500 for 2 hours work and the knowledge my father won’t bother me again with website designs