Backing up throws in the infield

For now I would suggest that you have your Rightfielder back up throws to first and your Leftfielder back up throws to third. I only recommend this because of the age you indicated (8-10). I coach a select 10 year old team and what we teach them is that with NOBODY ON the catcher also backs up the throws to first as well as the RF. We never have the Catcher back up throws to third. The Pitcher is responsible for backing up throws to Third and Home.

Which method you use should be based on the ability and maturity of the team, an advanced 10 year old and older team should be able to understand and execute the plays, however a younger inexperienced team probably would not.

Good Luck!