Dear N:

You wrote:

 1-I did not leave the house to see her.

2-I did not leave the house in order to see her.

Can’t these sentences have three meanings: a-I was supposed to leave the house in order to see her, but I did not do that. b-I left the house but not in order to see her. I left the house for another reason. c-I stayed in the house in order to see her. If I had left, I would not have seen her.

Could one use a comma after ‘house’ to make it clear that meaning ‘c’ is intended?

You are correct for sentence #2. It would depend on context. The comma does not really do much, but you are correct that putting a comma there would suggest an elliptical clause. Remember, these sentences in English are much clearer using clauses rather than phrases. Indeed, I doubt if any native English speaker would even say #1, though technically the grammar is OK. The expression “leave something to,” especially a piece of property like a house usually suggests an inheritance. For example, my aunt left her house to my sisters and me.

The short answer is, yes, you are technically correct, but English speakers seldom speak that way.