I think I understand the following:
At age 70, take my fra pia and multiply by last 4 colas.
Multiply that number by 1.32 to apply drc for 4 yrs.
The result should be my benefit if I didn't work after fra.(66)
Is it possible to get rule citations in case I need to educate ss ?

Hi. I assume you're referring to calculating your Social Security retirement benefit rate if you wait until age 70 to start collecting. If so, then yes that's basically correct, although dime-down rounding is done when cost of living (COLA) increases are added. Also, PIAs are automatically updated by Social Security each time a COLA occurs, so when you apply at age 70 your PIA at that time will already have been updated to include all of the COLAs that have occurred since you reached age 62.

Here are some pertinent sections of the Social Security Regulations, but I doubt if they'll be helpful or necessary: https://www.ssa.gov/OP_Home/cfr20/404/404-0271.htm, https://www.ssa.gov/OP_Home/cfr20/404/404-0275.htm, https://www.ssa.gov/OP_Home/cfr20/404/404-0313.htm. Virtually all Social Security retirement benefit calculations are automated, meaning their are no manual calculations involved.

Our software (https://maximizemysocialsecurity.com/purchase) includes a Social Security benefit calculator, so you could use the software to verify the accuracy of your benefit rate when the time comes.

Best, Jerry