回複：幫助了朋友夫妻團聚後可否撤銷我的一方的聯合經濟擔保？

No, you are obligated until situations not controlled by you. This is what 作保 means, you guarantee all the consequence.

You can however enter a contract with them and establish another relation between you two. Many divorced sponsors did that in their divorce contract, because divorce does not relief this duty to repay US even the GC-beneficiary soon to be ex-spouse now live with her new boyfriend.his new girlfriend, the citizen spouse(i.e. the sponsor) still have to pay for her/him. If money needs to be paid, you need to pay US government first, based on the contract between US government and you. Then you seek payment from them based on the private contract between you two. But if they really become spent-down to qualify welfare, you can still get no money even the court rules for you.