Ambiguous ownership when discussing multiple character body parts

Up front apologies for the vague title, happy for editing suggestions on that as I’m not sure how else to describe it. Apologies again.

I have come across a few situations where in a simple sentence I’d like to say that one character’s body part is doing something in relation to another character’s body part, all this without confusing which part belongs to who and which is making contact with who. Nothing weird here, please see example below for clarity:

1. John took Jack’s hand and placed it on his shoulder.
2. John took Jack’s hand and placed it on his own shoulder. (similar,
   but no less vague I’d say)

Now to me, this could read as either John placing Jack’s hand on Jack’s shoulder or on his own (John’s) shoulder could it not? Similarly in the second example, and my concern is this ambiguity. For example; how would the above look if John is placing the hand on his own (John’s) shoulder now? If John is now instead placing the hand on Jack’s shoulder that is straight forward. I could say the following, which looks unnecessarily verbose (every word counts) but it could be just me:

3. John took Jack’s hand and placed it on John’s own shoulder.

Is this the most concise solution or is there a better way I can punctuate or reword the above? Ideally I’d prefer not to split it into multiple sentences, but if (together) they aren’t any more verbose than perhaps that could still work. Thank you and looking forward to suggestions.