In the ChiroCode Online Library within ChiroCode Premium membership, you have access to a tool called the NCCI Edit Validator. This is a Medicare database that most private payers follow to determine which codes can be billed together and when modifiers are necessary. You can list all the codes you plan to bill together and the tool will identify which codes do and don't need a modifier and which ones can't be billed together no matter what. It turns out that no modifier will allow 97124 to get billed along with 97140. If a private payer allows you to do it in, say different body areas, you could try modifier XS for "separate structure" if that applies, but they may still reject it.