I'm being placed on my partner's policy. I have my own ins. via the union (I'm
Retired), but my union coverage converts to a medicare that is taken over by an
HMO and I don't that. I'll be 65 soon. Then they said, if anything happened to
My partner, I'd need COBRA and then hope my union will take me back.
Does that sound right? My partner's going on medicare as soon as she retires.

Actually once you turn 65 in the US you are forced to take the medicare of the US government, you can do it directly though the government or you can do a managed care plan though an insurance company.

After that you would have a medicare suppliment, so your partners insurance will not furnish you anything other than a medicare suppliment after you are 65.
I can not tell you what is best for you, but your parners insurance will not pay any more than your medicare suppliment, and if you do not take out medicare at this point,

I would have to see what HMO ( it will have to be a medicare program)
They offer, most are pretty good. If not, medicare with a private carrier like Mutal of Omaha would most likely be the best

I'm not sure where the forcing someone to go on Medicare comes from. We have several clients that have chosen to stay with the group plan they are part of and not sign up for Medicare. Some companies as part of their plan may request it.
It is beneficial, cost wise, to the company and the other participants in the plan to switch to a supplement plan if allowed. Groups of over 20 employees are not allowed to move active employees to a Medicare Supplement plan and they must remain on the group plan. A group may set up a Medicare plan for retired employees though.
Check your options on supplement plans, some offer PPO's and some of the newer FFS can work like a PPO. Also check to see if they are "Group" supplement plan and not individual plans. Group offer richer benefits.