Populating unlike fields in a Rowset

In the Peoplecode excerpt below,  like fields are copied from  &MYRS1 to &MYRS2. Let's say I have a field in &MYRS2 that's not part of &MYRS1. In a normal scenario those fileds will have a null value when copyto method is used, How do I assign a value to that field for all the record entries in &MYRS2 ?

Local Rowset &MYRS1, MYRS2;

Local String &EMPLID;

&MYRS1 = CreateRowset(RECORD.SOMEREC1);

&MYRS2 = GetRowset(RECORD.SOMEREC2);

&EMPLID = '8001';

&MYRS1.Fill("where EMPLID = :1", &EMPLID);

&MYRS1.CopyTo(&MYRS2, RECORD.SOMEREC1, RECORD.SOMEREC2);