If you have a factory kombi, with a 2+1 in the second row, you can fit a triple and feet in the 3rd row, with belts (Fixing points are alreadythere on a factory kombi - Need stripping and the panels need modifying). Or you can fit a shuttle centre single seat in the middle position in the rear, as this has the seatbelt integral - Both use the same mounting positions, or two in the very back row on on each side. The options are endless.
The other option to go Caravelle, as we have done in our demo (although with 4 single swivel Capetians chairs) is the next stage and a lot more involved, and certainly more costly, dependant on the cost of the complete kit, and they are not cheap.
We can do all of this, to VW spec, using all correct reinforcement bracket with a fitting certificate at the end. We keep some of the seat option in stock.
HTH