First a tiny bit of background. I have been an online retailer since the year 2000 for my full-time income, and used OScommerce for several years starting in late 2002. I am not a developer, but have made changes in code in the past for simple needs. Trying to avoid that in the future since real developers make core changes that break the changes I have made.
This is more of an informative posting than question since @Ivan Holbi has helped significantly. 2 issues that present similar but have different causes. I have need a very deeply nested categories.
1) creating 2 categories with the same name can cause odd switching of category results. This is caused by creating categories that OSCommerce generates the SEO automatically from the category title, and if 2 SEO's are the same results may not be what is expected
since subA is the same in 2 categories, clicking sub2, then subA may land you in sub1,subA
under the SEO tab assure that none are the same. In my case, I changed "subA" to "sub1-subA" and it completely resolved.
2) breadcrumb will change if products are duplicated across categories.
If a product is created in a particular category and then copied to another, selecting the product in the second category will change the breadcrumb to the first category.
Here is Ivan's response:
"The breadcrumb cannot display all the paths where the product is. It also cannot remember which path you go to the product. That is why the breadcrumb always displays the random (default) path to the product if the product is in a few categories. "
I have not determined a fix yet. I will post an update if I can figure one out, but this is a show stopper for me because of my functional needs. I am certainly not critiquing anything, just hoping there is a resolution and trying to help others.
Not sure if posting live link example is acceptable so I will hold off until I get approval.