Hi FED, so to make a network you would need to reconfigure your curves by cutting the bottom one in half using Edit > Trim so you've got pieces like this:



Then you'll be able to have 3 curves in this direction:



And then in the other direction you'd need to use Edit > Separate and delete the bottom pieces so you had the other curves set up like this:



Then you would be able to use Network, see attached file. But it will be difficult to avoid a kind of pinching effect at the "poles" in such a configuration.

- Michael