Create combined CpG and non-CpG bedgraphs for DNA methylation using Bismark

Hello, previously, I was using Bismark with the ‘–comprehensive’ option to generate the individual bedgraph files from which we made the bigWigs. For one particular figure, my boss wants me to generate merged bdg files so that we have one bigWig file at the end. Does this mean that I can add the score column of the individual bdgs ? Or do I use some option in the bismark_methylation_extractor ? Thanks