you have 2 options, a fast one which will increase the CP´s of your curve segment but having the curve chopped into millions i guess that might not bother you much anyway use Join and FitCrv with the same degree as the original curves and something like 0.1 tolerance, you may have to play with this to get the best result, if you go to high the curve will change of course you may even have to go lower to 0.01 but will see, after that it becomes one continuous curve with no end points other than as many as a sausage naturally has
second method is more handwork use match to match two ends together and choose continuity curvature then merge as an option will get available and it will merge the curves instead of join. you will have quite some knots more but you can use RemoveMultiKnot. just be aware that it can still be explodable at some parts so this might not offer you a complete continuous curve.
both are quite some work and i would suggest you to just keep the original curves on an extra layer or hide them and you reuse them again instead of joining tons of bulls excrements together.