Multiple biological reps per biomaterial

[mestato]

Currently, biosamples are loaded as individual samples from NCBI, and the module expects a one to one relationship for biosample to expression value. However, according to this page (https://www.ncbi.nlm.nih.gov/sra/docs/submitbio/, search for word "replicate") NCBI encourages submission of a single biosample with multiple replicates housed under that one record. How to handle?

In chado, biomaterials can have a “derived from” relationship, so we could create one biomaterial and your replicates are “derived from” that original sample. Need to work on how to implement in loaders and make sure display still works as expected.