I am dealing with a bivariate sample (~1000 elements, variables $A,B$) whose marginal distributions are known.
Each marginal distribution is assumed to be drawn from a semicontinuous distribution with positive mass at 0 and a two-parameter gamma for strictly positive values.
What is the simplest (in terms of no further assumptions) way to produce samples of $A,B$ which follow the explained distributions in a way they reproduce the observed spearman correlation?
Ideally, I would like to draw samples from A and then obtain samples of $B|A$ so that the correlation is kept.