Variant allele frequency with copy number

Question

[9521ljh]

the variant allele frequency(VAF) related to time-series, e.g. higher VAF related to early mutation, lower VAF related late occurred mutation.

However, if the copy number amplification with late occurred mutation, this VAF might high if mutation allele- amplified or low if wild-type allele amplified.

is there any tools to handling this kind of problem? to calculate corrected VAF?

[Ram]

I don't understand how higher VAF automatically means the mutation happened earlier. Can you explain that (or point to a paper) please?