Requirement on BP re determined in Trans that changes happed to source

Hi All,

Step 1.I have a requirement After saving the opportunity the BP (Contact person ) assignment should be copied to all the structure below (quotations and etc..). this requirement possible in the standard CRM systems. Because the date is copying from opportunity to quotation.

Step 2.Now if I change the BP( Contact person) on the opportunity level ,these changes need to pushed to below the quotation and etc.

Could any one please advise me how fulfill the step 2 requirement

Early reply would be appreciated

Thanks

Sai