Is the following possible

I have Table 1 with Field IDTable1 [autonumber] [and other fields] and Table
2 with Field IDTable2 [autonumber] and Field GRV set to text [and other
Fields]
Is the following posibble:
Can I automatically generate a number that can be used in GRV field of Table
2 consisting out of a combination of IDTable1 and IDTable2 written as
IDTable1/IDTable2 in the GRV field of Table 2, Example IDtbale1 [primarykey
autonumber] combined with IDTableT [primary key autonumber] automatically
written in the GRV field of Table 2 as example 12/100

I want this GRV number as a unique number identifying the data in Table 1
and Table 2

Thanks for your time