Hello Donford,
The easiest thing to do if you are really only concerned about providing a link to more information for the distributor's visitors is to nofollow that link. This way you're not going to chance getting "dinged" for adding 10,000 links all at once.
If you have a few product pages on the manufacturing site that you'd like to improve you can selectively remove the nofollow tag from the link pointing to those pages from the distributor side, but I wouldn't recommend 10,000 followable links from a single domain all at once.
Questions like this are always difficult to answer because Google doesn't treat every site the same. A well-known brand with thousands of high quality links and a trusted, established site that has been in operation for a long time with good user metrics, and has never been penalized can get away with a LOT more than a relatively unknown brand or an "average" site. That is why I recommend starting with the nofollowed links and, if you want, testing the waters by allowing a few of them to be followed.
Please let me know if you feel your question has still not been adequately answered.
Cheers,
Everett