There are two separate meanings I'm trying to convey with the following two sentences:
1) "I painted my brother sitting against the wall."
2) "I painted my brother, sitting against the wall."
My brother, in the first case, and I, in the second are sitting against the wall. At least, those are my intended meanings. Is this correctly conveyed through the addition of the comma in the second sentence? I know that restructuring the sentence can, of course, make it more clear, but this format somehow sounds nicer to my ear.
And as an aside, have I correctly put commas in the first line of my preceding paragraph? (The portion in bold.)