Yeah, definitely interested in a feature like this. Although I would take it a step further and allow me to designate that players are on certain lines, and from there filter my preferences on stacking / diversifying. For example in cash games I usually prefer NOT to take to more than one player per line unless it's a particularly good matchup, so if I could tell FC who is on what line and to not play more than one from each that would be really useful. Conversely, being able to force lines in the same lineup would allow me to experiment with different stacking combinations for GPPs.