There should be a rule in place to have the rosters of non-playoff teams locked through the end of the playoffs, but if there is no such rule then you are well within your rights to make a move.

Post is bang on.

If adding a player or players makes your team better, than you absolutely go for it.

Not sure I agree with that first point, especially if the provider shuts down after the season. If it's a keeper league, teams should have the right to make changes at any time during the season, regardless of whether they're in the playoffs or not. Playoff teams take on the risk when going for the title.

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All I've got...all I've got is insane!

I assumed it was a keeper/dynasty league. I run all my leagues as close to real NFL rules as possible. The NFL doesn't allow roster moves during the playoffs so we mirror that. You build your team during the season and roll through the playoffs with the guys that got you there.

I certainly have no problem with allowing all teams to be able to make moves, but there should be a league constitution that explicitly states what the rule is.

If it's just a random pub league then who cares? Do whatever the software allows.