Here are paraphrased versions of "Thanks #BOB, Welcome to BOB":

Appreciate it, #BOB — great to have you with us!

Thank you, #BOB! Glad to welcome you aboard!

Cheers #BOB, and welcome to the family!

Much appreciated, #BOB — welcome to the crew!

Thanks a lot, #BOB! It’s awesome to have you here!

Would you like it more casual, corporate, or community-style?

$BOB