is it possible to load historical invoices as accounted invoices into PJB from third party invoicing

Dear Experts?

I dont know if below if a stupid question.

But, please tell me if it is possible to load historical invoices as accounted billings/ invoices into PJB from third party invoicing system?

Because, we are implementing PJB now and there is a need to import ongoing projects actuals invoiced data into PJB for reporting but their accoutnig might have already been compelted prior prior this PJB activation already.

But, for the subsequent invoices, after PJB activation, we will import actuals sales from an inhouse built billing application by project (and by invoice number) as events and then generate invoices in PJB based on events > then accoutning etc will flow to AR > then to GL etc.