Is there a "common" ratio for dumplings and added water when adding to a soup/stew recipe? A while ago, I ran into this problem of trying to figure out how to adjust a stew recipe for added dumplings - I had made a dumpling recipe (for a family dinner), my brother had planned a stew, we could put one in the other to cook and be done.

Needless to say it did not work out.  There was not nearly enough water for both, which made the stew settle and scorch a bit on the bottom.  We hadn't been checking throughout, because the dumpling recipe in question (kinda) suggested a tight seal would help them expand and cook properly, and the stew recipe was alright with cover-and-cook.  We did manage to rescue it, by adding water, and gently loosening the stew back up - but the results were just a little bit watery, and the dumplings were a bit waterlogged and falling apart by the time the extra loosening happened... everyone said the flavor profile was pretty good, but clearly in the process of rescuing the stew, I had been a touch overeager on the added water.

I actually had made the dumplings before, but I had started with a very loose and brothy soup, since I was testing the dumpling recipe and flavor profile and avoiding distractions.  And my brother and I are both bad with recipes, but in different ways - I tend towards fast and loose, he is very by-the-book - so perhaps my quantity of dumplings was off (calculated for guests and not for amount of soup), and he had picked a recipe very specific on amount of water and cooking time.

So, is there some way to figure out how to adjust a stew/soup recipe for added dumplings?  How much water to add (per dumpling, or per volume of dumpling dough, or per volume of flour in the dough, or something) so it doesn't end up dried out, or watery?  Or maybe just how much liquid there needs to be in the stew in general per dumpling, etc, to make it work?  Anything needed to balance the seasoning of the extra water? I had thought not, since the dumplings and stew were both already seasoned, but if I am asking anyway... (shrug).

This is less about fixing that particular recipe combo, than figuring out how to make adding dumplings work for future stew plus dumpling dishes, since we have rarely cooked them in the past.  I figure there should be a way to adjust recipes generally, especially for those that need to stay closed to cook, which means they can't keep being checked along the way.  But if it helps, the dumplings were a (vegetarian) variation of a suet pudding, clootie dumplings rolled into little balls and free cooked in the stew, and the stew itself was a thick one of lentils and vegetables.
I have long since given up on trying to do this, because it varies according to stew/soup and according to dumpling. I have taken a different approach. Set aside some meat stock or broth, add water and bouillon or gravy mix for flavor, and cook your dumplings in that until they are almost done and don't soak up much liquid anymore. Then transfer them to the stew for the last few minutes, to take on the flavor of the stew.