Is it allowed in B31.3 to use the thicker TEE alone to reduce the stresses or do we have to use the thicker matching pipe for of some length with the TEE?

When calculating SIF in Appendix D Thickness of matching pipe is used for the TEE and Fitting thickness is used for the elbow and mean radius of the matching pipe is used for both elbows and Tees.

Appendix-D of B31.3 also says "(8) Stress Intensification Factors for branch connections are based on tests with at least two diameter of straight run pipe on each side of the branch"

Therefore it seems that thicker TEE alone cannot be used to reduce the stresses in B31.3
Similarly thicker elbow alone cannot be used as well.

Your opinion on this will be highly appreciated.