Help please - Airport Customs (Nonprofit Items)

Hello good people! I could really use the benefits of your knowledge and experience here.

My wife and I are planning to arrive in Zihuatanejo next week, and will be going through customs there. She is bringing two large tote bags containing 90 handmade washable menstrual kits that are going to be distributed locally to young mothers. These are amazing custom-sewn kits, each in a beautiful cotton drawstring bag, which my wife makes in conjunction with Days For Girls International, a US nonprofit that distributes these kits worldwide. https://www.daysforgirls.org/

My wife is coordinating the distribution through “DIF Zihuatanejo”, which is a local governmental agency of sorts (Comprehensive System for the Integral Development of the Family that promotes programs and actions for the benefit of the most vulnerable population).
https://zihuatanejodeazueta.gob.mx/dif

She will have a letter from Days For Girls that explains the organization’s mission and that the kits are distributed worldwide. She will also have a letter from DIF Zihuatanejo that explains that the kits are going to be distributed as part of their local program.

I’ve read about the concerns with the customs process in Zihua. My question is whether these kits should make it through with the above-referenced documentation. It would be heartbreaking to have them “seized” and not get to their intended recipients (not to mention the hundreds of hours of sewing and assembly labor).

Any thoughts and/or advice will be greatly appreciated. Thank you!