With the introduction of multiple guarantors to guarantees, bug 14570, now in 19.11, the relationship can not be edited from the guarantee from. Previously, a relationship and the actual guarantor could be edited from the guarantee form. Now in 19.11, there is no way to edit or change the guarantor from the guarantee form. The option that exists in 19.11 is to remove the guarantor not to edit.
Just noticed this today after our upgrade when we needed to change a father that was incorrectly listed with a relationship of mother. We definitely need to be able to edit rather than remove and then redo the info.
*** Bug 25740 has been marked as a duplicate of this bug. ***