CASIM: Variants Dealing with continual addition of data

[casim]

Given that it is more powerful to call genomic variants from multiple samples simultaneously than on a sample-by-sample basis, how would you deal with a situation in which samples are added incrementally (e.g. in batches) over time?

Is there a smarter, more efficient way of doing multi-sample variant calling after each increment that does not involve re-calling all variants genome-wide from scratch each time?