Split PO shipment line with an unreceived ASN line in PURCHASE ORDERS form

A Standard po line with a single shipment line which …

quantity ordered is 100 PCS,

quantity received is 10 PCS,

quantity shipped 20 PCS (from ASN line which line_type is 'EXPECTED' ),

which means onway quantity is 100-20-10 = 70 PCS,

I split another shipment line from the original with quantity 90 PCS while the original one remained 10 on the PURCHASE ORDERS form, it didn't raise any error and allowed me to approve the SPO.

Then I found that the original shipment line from po_line_locations_all table  in database: quantity 10, quantity_received 10 , quantity_shipped 20

the asn line from rcv_shipment_lines table in database : quantity_shipped 20,quantity_received 0 , shipment_line_status_code : EXPECTED