2 separate subnets from ISP

We currently a subnet from our ISP that got filled up so they provided us with another separate subnet coming in on the same interface.

I am guessing I will need to setup a static gateway route to direct traffic out the provided gateway of the new subnet since it wont go through the default gateway which is in the original subnet. I would then use DNAT/SNAT to get devices directed to the new subnet. Does this sound right? Never had a broken up range from an ISP before so looking from best practice on this.

Thanks,
Jim Koerner