Question on Closing Warp Points

[Enigma]

Well we are in a stock 1.91 game and I have been closing WP's single to single. I have done it a couple of times.

In fact I have a tactic where I open a Warp Point send in my ships and destroy a planet, leave the system, then close the warp at the end of the turn.

I will have to experiment with this other issue, but unfortunately this is a critical situation and if it won't work then I will have to do something else.