The short answer is no. You will not get fusion without slump.
That being said, there are excellent, optically-clear, UV stable epoxies that are made for this problem. Hxtal is the go-to for most. https://www.lakesidepottery.com/HTML%20Text/Tips/Hxtal-NYL-i...
It is very thin, and will happily wick in and fill cracks. Often the join is completely invisible. The downside is that the cure time is on the order of 1-2 weeks. It does take a little practice to use effectively, and it's worth trying on less-important projects first, but it's straightforward enough that you can expect success if you follow the directions carefully.