Multiple connections between a router and layer 3 switch

I have a router, which serves as a gateway for different WANs, and a layer 3 switch connected to it. The goal is to use the layer 3 switch as a 'router' for the devices connected to it, and to then forward WAN traffic to the true router. The general goal is to have a point to point connection between the switch and the router, but with a caveat. I'm trying to get two links running between the two with no luck. The router is set with two interfaces configured as a BVI, but I don't even know where to start with the switch. Creating a BVI isn't an option, so my thought immediately go to created an LACP with two switchports, and then assigning those switch ports to a vlan with an ip address for the point to point, but that doesn't seem to be working. Any help would be greatly appreciated