Need to default/auto populate Item in Sales Order Lines

Summary:

We have VTS(Vehicle Tracking System) devices which we sell.

Along with it, we sell VTS Connection SIM. 

There are different type of VTS Items say VTS_A. VTS_B.

For VTS_A Item, VTS Connection Item is VTS_Connection_SIM_A.

Similarly for VTS_B Item, VTS Connection Item is VTS_Connection_SIM_B.

All of these Items have been defined in Price List with separate prices. 

Item             Price 

VTS A             10000

VTS_B            20000

VTS_Connection_SIM_A     5000

VTS_Connection_SIM_B     6000

Busines requirement is, when VTS_A item is selected in the Sales Order Lines, System will automatically populate VTS_Connection_SIM_A.