Flange broken - Help!

Hi. I have a 4" lead closet bend with a broken flange set in a tile floor. I was attempting to replace the wax ring (to stop odor) when I noticed that the brass bolt head wouldn't stay in the flange once I tried to tighten the toilet down onto the new ring.

The lead is flared (hammered and/or soldered) around the inside edge of the busted flange.

If I put a plastic flange above the broken (brass?) flange, the toilet won't seat properly, and I'm hesitant to disturb the lead closet bend or its connection to the busted flange.

Any advice would be very much appreicated.

Should I try to repair the flange? It's cracked in only one spot, adjacent to the channel opening that accomodates the brass bolt.

Use a spanner flange that bolts over top of the broken area, this in turn "studs" the flange bolt in desired location. Looks just like a small piece of metal with 3 holes, 2 for anchoring and 1 for the closet bolt. Smear wax below, above and all around this flange to keep the condition of the flange from rusting. There are other methods to make this repair, one being unsoldering the brass ring and setting a new one if you can get the lead clean enough to adhere to the new brass.

lead

If it just hammered, shape the lead to make it a smaller o.d..
brush the lead and brass.
Flux and solder.
Try to screw the new brass flange to the floor.