I'm really newbie in 16s microbiome analyses, so sorry for this question. I would like to perform a meta-analysis using only Illumina Amplicons sequences from different studies that have different design. Specifically, I want to understand if is it possible to combine together V1, V3, and V3-V4 sequences. If yes, can DADA2 pipeline be used straightforward, or are preliminary operations needed? Since I'm an R user, please suggest libraries accordingly if possible.