Hi Eric,
Inspection lot with Status SPCO will always create new inspection lot, but as we dont see much options left here i would suggest a weird idea of keeping status of Inspection lot as SPST, Means do not complete posting until Last confirmation of order. if Order is of 100 Qty, then post 99 to UR and keep 1 Qty as pending, Post this Qty at the time of closing inspection lot. In this case system wont create New inspection lot.
Amol.