Software Deployment

I have a question regarding testing patch scenarios for our various products.  Let's say I have releases as follows...

Initial
January Hotfix
February Hotfix

The HFs are cumulative, small updates with no version change.

When I want to test that all goes well with patch application, I would test a matric like this...

Initial + Febrary Hotfix
Initial + January Hotfix + February Hotfix

I do this to ensure that the latest patch will upgrade the initial release properly and will update systems that had previously applied the January Hotfix.

Along with patches, we ship Full install suites for new machines or customers that contain all of the Hotfixes, of course.  So I would then test

January HF Full Build + February HF

My question is, is this secnario covered in the Initial + January Hotfix + February Hotfix listed above?  It is my understanding that when the January Hotfix is applied to the Initial release, it is in fact making it identical to the Full January Hotfix package used to create the patch.  So I would then not have to test January Full + February HF.  ??

Any info appreciated as I'm trying to streamline my patch testing processes!