Macro needed that's similar to IF formula

Good Day Folks

I'm trying to repair a spreadsheet that has been operated on with an axe as opposed to a scalpel.

I'm looking for a Macro that will work quite similar to an if forumla, with the caveat being that if the criteria is not met, it does absolutely nothing to the data already in that cell. I will need to run this macro in one column over 2400 rows. What I'm trying to accomplish is if column B contains the text "Left to Bill", I want it to insert a forumla on the same row in Column E. If column B does NOT say "Left to Bill", I want it to leave whatever data is already in that cell on Column E alone and to do nothing to it.

• Range of cells containing data is A1 to G2405. This data is a mix of numbers and text, as well as some empty cells as well.

• If Column B contains the text "Left to Bill", I want it to insert the formula =IF(AND(D6>500,(D7-D5)>500),"BILL CUSTOMER","") into column E of the same row. For this formula, the column is static, but the rows are relative. I hope I said that right.

• Presently, Columns B and C are merged together at any point where "Left to Bill" would be present (as well as a lot of other cell mergings at various places), but I can do a mass unmerge if needed. I'd rather not, but this formula is more important to me than the cosmetics of the cell merging.

Thanks for your time folks!