Wing Mirrors: Glass replacement/removal!

Morning ladies & gents.

OK. I have ordered "new" wing mirrors from a online breaker. They are in very good condition cosmetically. Just a few minor scuffs I have touched up.

They came as were described. So was not upset at the price I paid, but I misunderstood some information as I am, as you all know, a complete novice.

The passenger side mirror unit came "without glass" so I asked the guy how I would replace and was it easy?... I was told the "stick on" mirror glass is easy to fit.. It just sticks on. so I went online and have now ordered some. OK... simple so far.

I now realised my error. When he said "without glass" I did not realise it was just the original mirror clips to attach the mirror to, so obviously there is nothing to "stick" the "stick on" mirror to.

The mirror I am replacing is fine (as the mirror goes) is there a way to remove the mirror from the backing plate without breaking it? So I can use this on the better mirror unit? OR Is there anywhere to buy a mirror with the clip or another alternative?

Long winded I know but I feel detail is always good when asking kindly for advice.

Thanks in advance guys and girls.