Is this usage of 'for which' correct?

I recently typed the following to a friend in an email:

Last night I went to the theatre to see a play with X. Before that, we went for dinner at a nearby pub for which my cousin came along.

Now is that the correct usage of 'for which', or should I have used 'which my cousin came along to'?

I would avoid the "for which" entirely and opt for a more straightforward version of the story:

Last night I went to the theatre to see a play with X. Before that, my cousin joined us for dinner at a nearby pub.

In the most obvious interpretation of this, you are saying that your cousin came along for a nearby pub, which doesn't make much sense.

I would have said something more along the lines of "to which my cousin came along," yes. As this phrase follows the noun pub, it will be hard to avoid a dangling modifier here.

This sentence could most accurately be phrased along the lines of "Before that, we had gone with my cousin to dinner at a nearby pub."