I was about to re-run the mapping step to create BAM files with hg19 coordinates, but realised that perhaps it's easier to convert the existing GRCh37 BAM files to hg19 coordinates, without having to re-run the aligner completely.
I looked around for ways to do this but only find methods for creating chain files e.g. hg19-h38.
I would greatly appreciate some help with this. :-]