How to connect these DQS pairs when there is a mismatch?

Totally, we are storing 45 bits of data and 8/6 bits of ECC. We are using x16 DDR3L memory devices(4 Nos).

In first DDR3L - D0 to D15 data

In second DDR3L - D16 to D31 data

In third DDR3L - D32 to D44 data

In fourth DRR3L - 8 or 6 bits of ECC

Each DDR3L memory devices has 2 DQS pairs. Since we are using 4 Nos of DDR3L devices, we need 7 to 8 DQS pairs.

We have seen the "Pin information for the Arria V 5AGXMB1 Device" document. It shows only 5 pairs of DQS signals i.e, DQS6T, DQS7T, DQS8T, DQS9T and DQS10T in x16/x18 column.