Thanks. Another question I have is, do I also need to change the tags below or can I only change the SM tag from two different bam files:
RGID=4 \ RGLB=lib1 \ RGPL=illumina \ RGPU=unit1 \
These tags are also different that came from two original bam files. Can I only change the SM tag and not worry about these other tags for creating a vcf file?