"Sissification", at least as far as it is usually defined/implemented in games here, was never indicated as in the plans by Zorlun, even because honestly it seems something even more polarising than futa - one can have Myriam dom towards Marc, but sissification is another matter (disclaimer, I admit I for one have no interest in such a thing, though one could always relay on Zorlun's typical "can avoid almost anything", the problem in that case would be that he would need to split the Myriam DOM way in two, one with sissification, and one wihout).
At the same time, it wasn't with all the dragging etc., but there was at least one scene in the direction you want already (
in the pool scene with the boys, if Myriam is DOM and let the things go to sex, basically Myriam does stuff with the captain, and Marc is "cuckolded"), so, if that is enough for you, it is not impossible something similar may happen again (though the risk is that the ones that want Myriam DOM towards Marc, do not forcibly what that to be the recurring theme, Myriam dom in their relation is one thing, Marc being cuckolded all the time, another).