thanks for all the info LH, very informative indeed!You're welcome
With regard to the dual relay idea, I want to be able to switch up to 18A, so Im thinking to use an automotive relay? If it would be relay A that i would connect the load to, would that be the same side as the FETS's output? You can't use the contact that is connected to the FET. I'll answer this in more detail below.
To reduce cost, would it be feasable to use a lower rated relay for B? Yes Looking at the schematic I think both of them would be switching the high current - is that correct? No, The current for the logic will depend on the resistance of the relay coils you choose.
Thanks again!