dyeing thread, will it ruin the dyed cotton?

Hello, sorry if this question has been answered, i tried looking through back posts to find it.

I recently used black Rit dye to dye a white cotton jumpsuit black, it worked beautifully besides the thread still being white. I got the Rit synthetic Graphite in the hopes the thread will atleast stand out less. will what im imagining work? or will it ruin the dye i did previously? i imagined the black would overpower the graphite if the cotton did take any of the second pass.

thanks so much for any help