S/O-- Telling your contractor you're using another

[dac]

I didn't want to hijack the other thread, but I have a twist on this question I'd like to ask. We have a contractor we've used for a couple of big projects. He's redone two of our bathrooms, put in recessed lighting, etc. He's done a good job and he's also been really responsive when we needed help with odd job type stuff that most big contractors wouldn't touch. We're really pleased with his work and that he's been so helpful with other little projects. All good so far.

Here's the problem. We're considering a much bigger job of adding on to our house. This would be a major renovation and we'd be more comfortable working with an architect and probably a bigger contractor for that. How can we let the first one know and maintain a good relationship with him? I know he'd say that he could handle the job, but we're just not sure. He does work in our neighborhood all the time, so he'll see if we start something big. Also, it's not like we could hide the addition from him if we want him to come do a smaller project again in the future.

Thanks.