Storing for 3 weeks, then checking in additional luggage on Mexico airport

Question

My wife travels with a suitcase and a backpack on a return flight AMS-MEX-AMS (operated by KLM).
I travel a roundtrip AMS-SFO-MEX-AMS (operated by KLM/Delta) with just a backpack.

We meet in Mexico City. From there we will have a 3-week vacation in Peru, we together fly a return trip MEX-LIM-MEX (operated by Avianca).
During those 3 weeks she wants to leave the suitcase in Mexico, preferably at the airport.

So:

• My wife will arrive at MEX with the suitcase and backpack, leave the airport.
  
• A few days later she comes back to the airport with both, will want to take the backpack on to LIM but leave the suitcase behind.
  
• When arriving back from LIM to MEX (3 weeks later), she wants to pick up the suitcase and make sure that it is also put on the MEX-AMS flight.

Is this possible? Is there luggage storage in Mexico airport in the transfer zone, so that we can pick up that second suitcase when we transfer from our LIM-MEX flight to our MEX-AMS flight (we have approximately 4 hours transfer time)?
If not, what would be good alternatives? Is there storage outside the transfer area? Can she leave the area and 'check back in' with the suitcase? Or can she maybe arrange for a reliable local contact to bring the suitcase to the airport where she picks it up?

Answer 1

Among the Aeropuerto Internacional de la Ciudad de México FAQs is this question:

Where can I leave my baggage for a few hours?

At baggage storage lockers located near gates A and E2, which offer 24-hour, 365-day-a-year service. For more information, call 58028467 or 57869048.

If you have any questions please call 2482-2400, xt. 2260, which will support it. You can also write to comentarios@aicm.com.mx.

This FlyerTalk thread has expanded details:

BAGGAGE STORAGE

If you recover your baggage and have a layover, there are left luggage / baggage storage / GUARDAEQUIPAJE* at AICM, ~100 MXN per day. (*Goo-ARR-dah ay-kee-PA-hey)

Terminal 1: Internacional area 10 between Gates 7 and 8, Area E-2; 24 hours a day.

Terminal 2: in front of the Domestic Arrivals area, 24 hours a day.

And, although a bit older (December 2009), VecinaMex added this TripAdvisor feedback:

I phoned the airport locker company and they told me that each locker costs $ 100 Mexican pesos for 24 hours (aprox 7.70 USD) and that it fits 1 large suitcase or 2 medium ones; If you take more you can rent several lockers. They also tell me that there are always lockers available.

---

[Update by OP, June 2017]
We found and used the lockers between gates 7 and 8 in Terminal 1. You have to go to the lower hallway ('plano bajo') and they are easy to overlook. The pictures below show the lockers sign to look for.
Costs were 120 peso/day, paid in cash only; there are ATMs nearby. If the suitcase does not fit in a locker, or if you have to leave it for a longer time, they store it in an 'upstairs' room.