Is procrastinating with the first guarantor until confirming with the second guarantor, who offers to bring a relative for free, considered among the impermissible or legally prohibited sales?

If a person is compelled to obtain residency and finds no other way than to purchase it, there is no sin upon him, and the sin falls upon the seller. Based on this, there is no harm in withdrawing from the agreement with the first sponsor and entering into an agreement with another sponsor who provides residency without charge, because the first agreement is void.