Might have to give kittens away because of MIL’s allergies

Basically, my mother in law is extremely allergic to cats. She doesn’t really come over much, but we have to see her often and even though we change our clothes and even try to shower before visiting her, she gets severe reactions (her eyes swell up and become itchy, she has an itchy throat etc).

We’re having a child soon and so we will visit her even more because we want her to be a big part of the child’s life but us having kittens is affecting her health a lot.

Is there any last resort I can take to lessen the allergies before giving them away? I love them so much and don’t want to have to do that