I have faced the same issue. I was working on pre-work to migrate SYMDEV 77AD (R1) to target VMAX using SRDF.
But I was NOT able to add SYMDEV 77AD to DG . It was failing with below error:
"Cannot add the device to device group because it is a BCV Device".
When I checked device configuration I found "RDF1-BCV+TDEV". As device group was RDF1 type and device was RDF1-BCV so I thought of Migrating it using file rather than Device Group.
Work around : create a temp file Pair.Txt and run symrdf commands on that file rather than on Device group.
################
Pair.txt
#R1 R2
77AD 00EF
################
symrdf -rdfg 135 -f /home/puny/Pair.txt -sid 1950 query
symrdf -rdfg 135 -f /home/puny/Pair.txt -sid 1950 establish -full