You said...
It reminds me of people who need to add a million records in one batch, who drop indexes or something, to avoid a million REINDEXes.

I may be mistaken, but your idea seems resonable. You could make mass deletions in the three child tables without indicies if you deliberately track the group field in each child table. Yes, this would denormalize your data; it would require some slight modification to your data entry system to update the group fields in each child table. This minor concession would free your network of a lot of traffic and simplify your work to just four independent deletions and four independent reindexes (uh...reindexings???).

Please help me learn from you. What is this RI? I cannot find it on the help index. I looked at all the R's in case it might be some interface like reindex interface. Nothing comes close. Thanks for your help.

(Also I respectfully submit that the plural of index is indicies. I feel it is a lost cause, but I keep trying. I hope this is in good taste and does not violate our UT rules.)