Billing Matters - can you add on after initial purchase of Time Matters?

I have a colleague firm that recently purchased Time Matters 9 Pro, and are now interested in purchasing Billing Matters to go along with it.  I see on the TM website how to buy the package new, or either new - but can anyone tell me if they can now add on.  I believe their initial purchase was in mid-January this year.

Thank you in advance.

As of now, yes you can add Billing Matters,even if you own Time Matters the add-on is considered as buying it new. If you are not comfortable with the order you can call Time Matters sales or a CIC for assistance.