steps to reproduce
1. create RMA - No1
2. void RMA no1
3. create RMA no2, try to select shipment line (previously already selected on RMA1)
remark: when test i run the next sql
update "adempiere"."m_rmaline" set "m_inoutline_id"=null where "m_rmaline_id"='1001751'
this release line for - in my example to RMA No2.
suggestion: improve create lines from on RMA window - list m_rmaline where m_rma.docstatus=VO