Stacking two datasets and writing the result into one of the input datasets.

I have a case where I stack two datasets but the output of the stack operation is one of the input datasets. For example, I have Datasets A and B, I stack them and write the result into A. However, the output is only created by B, in other words, previous rows from dataset A are lost. Is there any solution for that without using any script, with just using stack recipe? I am able to use the same datasets as both input and output in other recipes, but in this case, the stack recipe does not seemingly work in that way.