You can't, as soon as you will try to do any transfers it will flag 4 players of one team errorUsing this thread which appears quite generic.
I selected Solanke a few weeks ago, as I was messing about early selecting my team ahead of the season, he was a Bournemouth player then. In my picks I've already got 3 Spurs players, now that we've bought Solanke I've got 4. But having logged in FPL seems perfectly Okay with this, there's no message saying that I can only have 3 players from one side.
Q: If I leave it as it is (4 Spurs players) are FPL going to fuck me somehow?