Hi can any one give me advice on a 3rd row seat my van is lwb so drilled holes 4 r on cross member the other 4 r in side the rear trailing arms the metal looks to be 3l ayers thick in there do I need to try and get plates in there here’s the picture below of the holes inside trailing arm box section on the other cross member was advised to use the single brackets 7H0803547A so I have fitted them and riveted to the van just want to make sure it’s right with my kids in this seat any help would much appreciated thanks