What you have to do is have a draft of the 8 teams players. Allow the 8 teams to pick 2 keepers that can't be taken. Then the 2 new teams pick 3 players each with no more than 1 player taken from any 1 team. Then the teams freeze 2 more players and you do the draft again. Something along those lines until the 2 new teams have the same # of players as the others.
Depending on what site you use you might be able to allow the 2 new teams to have the first draft picks the first few rounds as well. Maybe be able to trade a draft pick for a better keeper. You should be able to do something along these lines to allow the 2 new teams to at least have a decent shot at competing. The more you do to help the new teams the better
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