Amir, if the drain is connected via the second skimmer port, I doubt you'll be able to blow the whole system at the same time. The MD line to the skimmer needs to be treated separately - this is easy enough to do. Get a male adapter and glue a ~ 15" piece of ridged pipe into it, wrap the threads on the M/A and screw it into the MD port on the skimmer. Blast air through the pipe until the MD bubbles for ~ 30 seconds and quickly!! slam a plug into the line, if ti takes too long to get the plug in, the water will rise back up to pool level and you'll have to do it again -- using one of the premade 'expand-n-purge' plugs will enable you to 'blow - and- forget' it

Where is your water level as you do this? You sound like you almost have the whole thing down, but need just a little 'tweak' to get it ' 100% ' - if you can't get it done by tonight, just run the pump to keep the water from freezing in the lines -- you're probably just going to ~31 deg, the lines won't freeze solid at that temp, you may see a 'skim' of ice, but nothing to damage the pool, pipes nor filter system. You still have some time to winterize correctly!!

Please let us know how it goes! - Ted