Hello everybody!

I am currently creating my own race and I would like one racial trait to be:

• You can add half your proficiency bonus, rounded down, to any Stealth ability check.

I found correct settings to give a skill half proficiency (E.g. add racial trait -> add a modifier -> modifier type = half proficiency -> modifier subtype = stealth). But not to add half the proficiency to a skill on top of it, if one choose stealth as a regular proficiency. Is there a way to put the settings to achieve the result I intent to? Or is that not possible with the current possibilities?

For example, if my race has +2 DEX and Proficiency Bonus +2, this would be the values I expect:
regular stealth: +3 (+2 Dex, +1 half prof)
stealth if proficient: +5 (+2 Dex, +2 prof, +1 half prof)
stealth if proficient and say rouge expertise: +7 (+2 Dex, +4 prof, +1 half prof)

Hope that is understandable. Sorry for my bad english ':D

I understand, and your English is fine. Unfortunately, there is currently no way currently to do that. The game was designed to specifically not do that, and this website was built to match the game. Things may change soon, don’t know. I would recommend leaving a request for this here where they collect these requests: 

 https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/21916-what-additional-modifiers-would-you-like-to-see?page=18

Thank you IamSposta! :)

Sorry I couldn’t be more help.