Hi Mrxlazuardin,
If you need to setup stacking with SummitStack-V320 between the two X770s & two X670s, each of the X670s need to be Summit X670V model and will requires a VIM4-40GX installed in each X670V switch. So please confirm if your X670s are X670V. And if so, please refer to the following GTAC Knowledge base article that has a link to the Stacking Tool (can be used to simulate different stacking scenario and compare capabilities including table sizes/modules needed and EXOS versions supported:
https://gtacknowledge.extremenetworks.com/articles/Q_A/Where-Can-I-Find-the-EXOS-Stacking-Tool
Please explore/use the Stacking Tool to compare options for stacking using a combination of switch platforms.
If your X670s are X670V and you have the VIM4-40GX installed in each X670V, please refer to the following GTAC article on the exact steps on how to best stack X770 & X670V (with a VIM4-40GX installed). The article assumes that you have one X770 & one X670V (with a VIM4-40GX installed) but the steps can be modified to include additional stacking nodes, as mentioned in your scenario:
https://gtacknowledge.extremenetworks.com/articles/How_To/How-to-build-a-stack-of-Summit-X770-and-X6...
If the X670 you have are not X670V model then the are not capable to support SummitStack-V320 and can only support SummitStack-V. If this is the case then it may be better to have two separate stacks (Two X770s in stack and the two X670s (non V) in another stack.
Please let us know if you have any questions.
Thank you.
Best regards,
Andrew