Auto populating duplicate data

[Triple]

I would like to know if it's possible for a script to auto populate certain fields with the same data based on matching ID's. I have a "parent" record which has a variable number of "children" records. I would like to be able to enter one address on one of the "child" records and if that address matches the other siblings addresses then a script would auto populate the siblings with the same address.

This may be done fairly simply, but I am a bit of a newcomer to developing and just am not sure how this would be done.

Thanks

[Fitch]

One way to solve this is to store the address in the parent record instead of the child. Would that work for you?