On " Voitures Bugatti aux pays tchéques" :
III° National hill-climb Knoviz-Olsany 1926: T35 #4328 : Eliska Junek 4th
IV° National hill-climb Knoviz-Olsany 1927: T35C #4831 : Eliska Junek 3rd
V° National hill climb Knoviz-Olsany 1928 :T35B #4868 : Eliska Junek 6th
On the photographs: the Bugatti with NV 437 is for me 4572 in 1926,
4572 is used before the 4831
(4831 different of 4572, or 4572 Modified in 4831 ?).
4831 with N 498 from 4328.
I do not believe 4328 with three registrations :
N 498, NV 433 and NV 437 , only with N 498 and NV 433
On the second, third and fourth photographs it is probably not in Knoviz-Olsany 1928.
For Knoviz-Olsany 1928:
The book " Voitures Bugatti aux pays tchéques" specify that it is T35B (4868).
4001 with N 469 (also used by 4059)
4059 with N 469
4328 or 4329 ?: with N 498 (used then by 4831), and NV 433
4815 with ?
4572 with NV 437
4831 with N 498 from 4328
4868 with ?