We took our twin babies when they were 7 mos. old and 13 mos. old. Here is what we did: We mailed a huge box to our resort, via US Priority Mail, filled with diapers, wipes, food jars, travel cans of formula, etc., etc. That stuff alone saved having to bring another large piece of luggage. And it was all stuff that we would use while there, so we wouldn't have to worry about re-packing any of it.
We mailed the box about 10 days before our arrival date. I pre-called the resort to ask for the mailing address and confirm that it is okay to mail a box to myself. I was told to simply put on the package to "Hold for Guest (name), arriving on (date)."
Everything worked very smoothly and we wouldn't hesitate to do this again. The box was at our resort waiting for us when we arrived. Your kids are a bit older than mine were, so your situation may be different. But if it does make sense for your situation, I highly recommend doing this.