You are trying to add a child record when there is no parent record thus the error. I cannot tell from that which is which or even if you've identified the parent table or field. If the parent has something to do with DateKYCCommenced then you have begun a record but haven't saved it before trying to append the child via the recordset. You'll have to save the record first. If Me.Dirty Then Me.Dirty = False might fix the problem if I'm on the right track.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.