Merging multiple loom files with different reference genome

[yechanYS]

I've been trying to merge multiple loom files into single loom file using combine() function from loompy module.
However, since my samples were sequenced using different reference genome (hg19 and GRCh38), the error occurred repeatedly saying that the number of rows are different.

ValueError: Layer has 36601 rows but file has 32738

I confirmed that the samples which have same reference genome are merged successfully.

Is there a way to merge multiple samples with different reference genomes?