Welcome to the site. I usually don't tie up because I feel that it may make the larger fish or most of the fish move off the tree due to the boat pulling on the tree. I like to fish the entire tree so I just work around it or if its not that big of a tree I'll just fish the entire tree from one location. As for getting you and your dad on the same tree have him fish the front of the boat next to you. Just my two pennies! Again welcome to the site.
"If people concentrated on the really important things in life, there'd be a shortage of fishing poles."
Dave