New party to contract

In the middle of an escrow and the buyer wants to add thier spouse to title but the spouse will not be on the loan. An ammendment to escrow was created and the seller asked to sign it. The ammendment basically states the above, that the spouse is being added to title as a joint tenant and that the spouse is aware of and agrees to the terms of the purchase contract. It does not saying anything with regard to disclosures or agreements made after that point.

The purchase agreement and all disclosures have already been completed with original buyer. The lender has no objections to the spouse being added to title I am told.

My question is - when is the spouse added on the title? Does escrow continue with the original buyer until they close, have everything recorded as usual, then as a last step record the spouse on title as a joint tenant? Or does the spouse sign an agreement with the lender during escrow saying that they take title subject to the lenders interest?

I ask this because I need to know if I need to redo the disclosures and include the spouse then have them resigned. Also need to know if I need to include the buyer and spouse on all remaining paperwork throughout escrow.

Thanks