Tadka's relationship with Ravan

[Avinash 0]

I have read it written in many places that Tadka's sons Marich and Subahu were Ravan's maternal uncles, which means Tadka was Ravan's maternal grandmother.

But I read in Valmiki Ramayan that Tadka's husband was demon Sund. This means Sund was Ravan's maternal grandfather. But how is it possible? I am aware of only three grandfathers of Ravan - Malyavan, Mali, Sumali.

 

I have also read that Tadka was Sumali's wife. But Valmiki Ramayan says Tadka was Sund's wife. So, how do we reconcile these differences?