I would separate them and grow them as individual plants. Also, when you separate them and repot, I would try to amend the soil with perlite or more bark to make the soil drain faster. I bought a similar plant a few back, and here's what I've done with them.
{{gwi:94171}}

Don't sweat the small stuff....while not ideal, I've forgotten to water my "clump" of PT's several times and they only start to shrivel a little. Yes, some leaves may turn yellow, but a good drink always plumps them back up. PT's grow very slowly, so it is up to you whether you want to separate them or not, and no, they won't fuse into one giant bulb. When you repot, you should generally only move up one or two inches in pot size, but with the grouping you have there, I think you did ok. I agree with Whip in regards to the perlite though; I would make a 50/50 mix. You can repot again if you need to, you won't hurt the plant. I, personally, would plant them higher in the pot...they look to be much lower than the lip. You do have them adequately covered, so no worries there. You have a nice little collection.

Nancy

One thing I can think of that would be of some assistance is to be mindful of how much you water in the winter. They will need a good bit less than in the spring/summer (as with any houseplant), but since they store water a bit more than say a peace lily (in their "bulbs"), they can easily rot if kept too wet in the winter. Trust me, I've killed a dozen or so already. >.Planto