Swallows Nest

Last year, for the 1st time in many years, Swallows built a nest in the overhang at the front door. Over the autumn and winter, at least 10 Wrens, yes, I could not believe it, until I counted them one night, when I put the outside light on, were roosting in it. They are still roosting in there. On Saturday, I saw the first swallow return (last year it was a good 10 days before I saw the partner arrive back) it was sitting on  the overhead cables. The nest is still well attached to the wall but is a bit ragged at the entrance, with all the Wrens being in there. Do I leave the nest alone and they will reuse it, maybe with a bit of updating or do I knock it down now, before the 2nd Swallow returns and they start to use it or rebuild? What about the Wrens then? Any advice greatly appreciated.

Beauty is in the eye of the beholder.