Is this MMR-abuse? (Blackrock)

So as the title says.

We are a 3vs3 team on Blackrock. This weekend our lock can't play, but me and the other guy want to keep playing in the same team with a new guy for the weekend only. But my partner said that this may be considered MMR-abuse? This makes no sense to me.

Would this be categorized as MMR-abuse, to add a new player to the team when the team already has a lot of games played?

No it won't be mmr abuse since you add one player to team to do games while one of your members are gone.