How about distinguishing permanent and temporary ties? Are they distinguished now? Maybe by thickness?
I am not sure what the graphical abilities are, but I was thinking about this: if two bots are joined by permanent tie then draw them as a pill (basically make the tickness of the tie equal to diameter of a bot). Of course, the problem is with bots of different diameter... Can you make the tie to taper off at one end?
Also, in the pic you showed with five bots all linked to each other. How difficult would it be to detect those small triangles of empty space and color them in, so that multibot looks more solid? And here's something not related to graphics: what if we make ties to exert some friction on bots? So that the bot in the middle of such glob (even when it's not hooked up by ties) would be dragged along simply by the fact that there are multiple ties overlapping it.