You can "reset" delta on an CR on two methods ( I use the firs one ) :

Set number of full backup interval, under Advanced settings (left down). And can be predicted as fallow
Reset = full backup interval / number of delta per day.
So for 4 deltas per day
Reset = 21/4 = 5 rest 1, reset will be on day 6 on first backup.

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Or on schedule on Replication retention

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Force full backup is to force full backup on next run