Hello Robert,
if dialog B is presented in context of dialog A and dialog A is dismissed, also the dialog B will disappear from screen. Furthermore, if there is no other reference to A or B retaining the objects alive, the objects are also discarded by GC. If you want dialog B to remain on screen after dialog A is dismissed, don't present B in context of A. Instead present it in context of e.g. the owner of A.
Does it help you further?
Best regards
Paul Banach