If you present a contract to the hospital and explain that these are your terms, and a reasonably understood officer of the business signs it, then sure: they're on the hook. Contracts are contracts, and the law gives great weight to consent, even in circumstances like this where it's not clear a real negotiation happened.

The idea above was about "swapping" some random document in for the standard form and presenting it to them as if it was their document. That's not good faith negotiation, that's just fraud.

You don't need the new document to hold up in court, the gambit is to deprive them of having your legal agreement.

Granted, a court might still see that as fraud, IANAL.

And again, refusing to sign a contract while presenting to a business as if you did for the purpose of getting out of the payment agreement is simply fraud. It's not even arguable.

If you gave back a different form and the hospital doesn't bother to check it's their fault. Sending back amended contracts back to back during negotiations is completely normal.

There is a difference between informing them you are modifying it or sending back a clearly edited version and stealthily modifying it in the hopes that they won't notice.

I don't think it's going to hold up if you surreptitiously modify it in bad faith.