As for my sister and nephew, if it's easy to add them back I may end up removing them as well. It's just annoying how they show up in the middle of my friends and family, so it costs me precious seconds when going for a boarding group. Without them now I can just hit select all and go for it... I'll take every advantage I can get!!!
In case you already didn't know, as long as everyones has a valid ticket and park passes for the day you are there, you and your guests will automatically be selected during the boarding group selection process and you'll only need to hit the Join button - if you are just practicing, it won't help you to select anyone else.