I have two questions:
1. With American buttercream, is there a way to make it stiffer without making it too sweet? I used the following recipe:
6 oz cream cheese
3 oz butter
2.5 c confectioners sugar
0.5 t vanilla extract
The recipe also called for a few tablespoons of milk, but I didn't use any because it was already too thin. It had a nice flavor but I ended up adding another cup of sugar so I could spread it on the cupcakes, which made it too sweet for my taste -- and still much too thin to pipe with. Any thoughts?

Also:
2. Is there a way to thicken SMBC or IMBC after you've made it? I often have trouble piping roses or other things that need to "stand up" and don't know how to modify the recipe or my technique to make it work.

Thanks!!!

Have you tried cutting down on the cr ch &/or butter? Cr Ch icings are usually very thin Also, what is sweet to one is not to another. I have a BIG sweet tooth so it would not be sweet to me. Ooohhhh just thought, did you try putting it in the frig for an hr or so to stiffen it up some? That might work.
I don't make IMBC so can't help there.....except the same idea, put it in the frig for awhile to stiffen it some.

only 2 1/2 C of sugar?? You could try adding more sugar and a less cream cheese.