My company has several websites but we only nurture leads through one domain. I would like Marketo to track activity from all of our websites but we would never send emails or nuture from our subsidiary domains, just the main one.
For example, we currently have 6 websites:
DomainA.com - lead entry point, main website that talks about all products and our whole platform
ProductA.com - Subsidiary company
ProductB.com - Subsidiary company
InvestorRelationsA.com
InvestorRelationsB.com
InvestorRelationsC.com
Should we install the same munchkin code on all 6 websites?
Yes, I would definitely implement Munchkin on all your domains.
Which sending domain you are using for your emails is an entirely different setup and not related to the Munchkin script.