Apple care+

And what is your question exactly?

If they are ineligible, then you cannot get coverage for them anymore.

You have 30 days once Apple Care+ expires to renew it into an ongoing monthly subscription

click here ➜ Extend your AppleCare+ coverage - Apple Support

The regular 1 year warranty can only be extended with Apple Care+ to 2 years, within 60 days of having purchased the device in question from Apple or an Apple authorized reseller.

click here ➜ Buy an AppleCare plan - Apple Support

Do your devices fall into either of those 2 scenarios?

All devices carry 1 year warranty from the date of purchase.

Again:

1. You have 60 days from the moment you purchase the devices from Apple or an Authorized reseller to purchase Apple Care+. If you did not do it within those 60 days you can no longer get Apple Care+ for them.
2. If you did originally get Apple Care+ for them and it expires (after 2 years), you then have 30 days once it expires to extend Apple Care+ into a monthly service.

If you are in neither of these scenarios, then no, you cannot get Apple Care+ for them anymore.

If you wanted them to have coverage you need to have bought it while it was possible to do so for them.

You can't just randomly buy coverage for them when you think you need it.