First, let’s clarify the Hanoverian terminology:
Register = certificate of pedigree.
Approval = means they’ve been inspected, approved and entered into the studbook and thus they’re allowed to be bred and produce foals who can be registered as Hanoverian.
So, in Hanover, any non-hanoverian registered horse that has an xx beside their name is Thoroughbred.
If a Thoroughbred is listed in a Hanoverian pedigree who has produced a “Hanoverian registered foal”, it means that Thoroughbred horse was inspected by the judging committee, approved, and entered into the studbook. No horse (TB or otherwise) is allowed to produce a registerable foal, except that the mare/stallion has been inspected, approved, and entered, no matter how nice the foal might be.
Most Hanoverians have some TB blood in their lineage.
FWIW - Your horse is probably named a W name after his sire in deference to his particular family tree. Weltmeyer is a rather good family to belong in.
Ansturm sired by Adlerfarn II was a fully licensed Hanoverian stallion who was sired by the Hanoverian-approved Thoroughbred Stallion, Adlerschild xx. Adlerschild was sired by the racing stallion, Ferro xx.
Ansturm’s Hanoverian dam, Paulette, was sired by the approved Thoroughbred stallion Poet xx. Her damline is very good - Stamm 191 - this stamm line produced the likes of Bolero and Hitchcock. Bolero basically turned the world upside down in his day and age and some of the very, very best dressage horses have Bolero within the 3rd-4th-5th generation of their pedigrees.
The “A” line and the “W” line tend to nick very well together.
Therefore, your horse does have a fair bit of thoroughbred blood in him, a good mix of blood and his pedigree top and bottom is rather nice. You have yourself a very good sporthorse pedigree.
Congratulations on your new horse. 