Well, I can't say I recommend my setup. I am in the process of scrapping it as we speak! But for what its worth:
-I scratch built most of my armor, including the grenade straps. They were from a backpack which I secured within the space between the sections of belt where overlap occurs (The overlap in the adjusting area).
-So I folded the end of the backpack strap around a wide flat piece of plastic and put the whole thing between the layers of belt.
-I then tightened the metal slides on the belt over the area where the plastic and strap were, was essentially sandwiching the plastic (which itself had the strap wrapped around it) between the two layers of belt.
You may be able to see in this pic that the fabric on the belt was so stiff it loops rather than folds flat on the buckle connections. Once I added plastic and straps to the mix of 2 layers of belt, then through an ab pad under it, it all was quite rigid. Nothing intolerable but now worth replacing for sure.

Now that I have a softer belt I went ahead and got some of Spat's grenade straps that will just loop over the top. Mine was a good setup on a budget, I will say that. It looked OK when standing. But its time to move on.