Start your Creation Kit.
Load Skyrim.esm and Load wolverineclaws.esp and set it as an active file then go to the object window click on character and menu will pop up. There find a file called Race and double click it find your mutant race in the list in the right corner of this window, double click it and the detailed information of this race will show. all you have to do here is to find the text field in this new window which should be located on the right corner with a title "Keywords" go there right click in the empty column select "Add" and type the word "vampire" into the filter. It will find a reference called "vampire" click on it, click on OK and this reference should be now added to the Keywords field right under the "ActorTypeNPC" then close the whole race window by clicking on OK button and save your work Enjoy playing Dawnguard as a vampire with your custom race

Anyone having trouble doing this let me know.

i dont get how to do that. Is there something u can do to make it simpler

i cant figure out how to do this,

I could answer your questions.

For Users: go into the race screen inside the creation kit (where you edit the races) then add the keyword vampire inside that box on the right side inside the race menu. This will make the race reconized as a vampire race and you will be able to play as a vampire.

For Dev: Incase you needed some help to fix this issue more permenantly...create a duplicate of your races (mutant x, wolverine ect.) and on those duplicates put the vampire keyword. Next enter the quest PlayerVampireQuest and edit the script with a couple of lines to include the new duplicate races you made (so the new races are added to change into vampire varients, when bitten they will change). Add the corresponding properties to the script (example mutant x and mutant x vampire races) and voila your races will be fixed and ready to become vampires. Just make sure that you specify to put your mod lower than the vampire overhaul mods in the load order because there will be some clashing issues as they may edit the same script. I'm not sure how well this fix will work with other vampire mods so I suggest to back up your current mod before doing this fix to see if it is worth implementing or not.