How to setup common TDS thresholds for different suppliers with same PAN number

Dear Guru's,

Require some help on this:

Our senario is like this.

We are procuring goods/services from a Marjor supplier along with its sister concern.
But both of them are using the same PAN.In our case both of these party locations are also different.

So we have mandate requirement, to use the same threshold slabs with the combination of these two parties.

Say there are two suppliers named as
1. A
2. B

we have some concession rates upto Rs.8,00,000 which needs to get substaniate the transactions of both these parties.

For each validation of invoice, TDS rate should get derived, by considering all the transaction of both the vendors (A&