Does an increase in the value of the gifted object, resulting from the son's action, prevent revocation when the object was gifted while the son was in possession?

Primary text

If the value of the object increases, it is considered an attached increase (ziyada muttasilah). Whether this prevents revocation depends on differing narrations regarding fatness (sumna). However, a strong possibility exists that this increase prevents revocation in all cases because it results from the action of the son, thus taking the place of the object itself gained through his action. This contrasts with fatness, which might potentially belong to the father, thus not preventing revocation because it is an increase of the object, following it.