If your VWL and SSR contracts are under the same membership (same base contract number with different extensions such as 12345678.1, 12345678.2) you can just combine the points at 7 months out. For example, you could book a night that cost 12 points using the 7 SSR points and 5 of the VWL points, or whatever combination you like. Similarly if booking several nights, you just choose how many points you want to use from each contract.
If the contracts are under different memberships then you would either need to book whole nights from each contract and link them or transfer points from one contract to another.