Improved Familiar Level Requirement
 

I am playing a campaign as a sorcerer and we have encountered a ratling that really wants to be taken as a familiar. I am currently a level 6 sorcerer. As I do not have access to a familiar from my bloodline, I was going to take a level of wizard at level 7. It would give me access to a familiar, a feat to take improved familiar, and the requisite seven levels to be able to take a ratling specifically. However when I do so, I get a validation error that I must be level 7 to take that familiar. I am trying to figure out how to adjust it so that the familiar adds properly. I tested with a level 8 character, 7sorc/1wiz, and got the same error.

So questions:
Do I have to be level 7 with the class that gives the familiar in order to get the improved familiar?
Is there any way to do an adjustment in hero lab to remove the level requirement needed to take a ratling for a familiar?

Thank you

Yes, you will need 7 levels in Wizard to get that familiar. Your Sorcerer class doesn't stack since it doesn't grant a familiar.

HL messages in red are just warnings not hard stop logic. This means you can just add the rattling to your character with out needing to be level 7. You will just have a warining message about it on your character.

Yes. See the "Level" entry in the Core Rulebook p.12. It seems that you're confusing class level and character level. Your character level 7 PC needs to have 7 class levels in Wizard in order to get that improved familiar.
It's the same reason a Fighter 6 / Wizard 1 doesn't get 4th-level Wizard spells.