Will the comma suffice to indicate whether the subject or the object is being modified?

Question

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.)

Answer 1

To me, in the first sentence it is clear that it is the brother who is sitting.

In the second sentence the comma has introduced an element of ambiguity, so I am now not sure who is sitting.

If the primary goal is to be unambiguous, there is no getting around reconstructing it. For example:

Sitting against the wall I painted my brother.

(In answer to your other question, there should be a comma after 'second'.)

Answer 2

When I first read the question, the thing that jumped up to me, was that the two sentences meant different things. Then I read "Is this correctly conveyed through the addition of the comma in the second sentence?" and I have to say that it was absolutely clear to me. However, as you say, it might not be very clear to others. The answer is, yes, it does convey your message, but I will suggest:

I painted my brother while sitting against the wall.

The comma works, but for people who aren't that good at English, they wouldn't spot the difference the comma makes, so I would advice you to "make it obvious".