Welcome to the Community @nalakatos. First, a +1 for what @EugeneAtKiwi offered. I think associations and customizing your record + index views will help.
For a little more thought to maybe help, I don’t think yu’ll be able to get a true “dynamic dropdown of just that vendor’s contacts” with native properties as you describe. But here’s how associations plus record layout customization should help.
If you have Enterprise, here’s how I’d set your objects:
Vendors: custom object (or use Companies if that fits)
- Associate Vendors ↔ Contacts (all people at that vendor).
- Associate Vendors ↔ Projects (so each Project has one Vendor).
Projects: you may have this already, or it can be a custom object
- One association label to Vendor (“Primary vendor”).
- One association label to Contact (“Vendor contact”).
This keeps your “who is the vendor?” and “who is the main person there?” cleanly separated without a giant contact dropdown.
Now, here’s how I’d think about how users actually pick “vendor then contact.” You can get the UX you want by driving the workflow from either the Project or the Vendor record.
Option A: Start from the Project
- User opens Project 1.
- In the right-hand sidebar, they use the Associations area to search and select Vendor A (your Vendor object).
- Still on the Project record, they use the Contacts association card to search and pick the correct contact.
Result: Project 1 is linked to Vendor A and one Contact; that Contact is already linked to Vendor A via associations on the Vendor record, so you always know “this person belongs to that vendor.” The good thing for this set-up is that there’s no custom dropdown properties to maintain, it scales well as you add vendors/contacts, and it works entirely with native HubSpot association UI.
Option B: Start from the Vendor
- User opens Vendor A.
- On the Vendor record, they see the association cards for Projects and Contacts.
- From Projects, they create or open Project 1 (now associated to Vendor A automatically).
- From Contacts, they pick the one person to associate to that project (via the Project’s association card or from the contact record).
This workflow feels closest to “choose vendor, then choose someone at that vendor,” because they already see just Vendor A’s contacts on that card.
Hopefully that gives you something to think about. I’m a fan of custom objects for something like this, using more than just the Contacts object if possible.