If the small wire is loose where you can slide the tool off the other end you can use a Buchanan splice cap they come in 2 different sizes. The larger ones and more wires are tougher to squeeze with the tool.

Most of the time in connections though they need to all come in one side of the cap.

Otherwise a  larger compression squeeze sleeve could be used or one of these threaded type connectors.

I learned from the best my Dad was a lineman, then lineman 1st class, then a regional safety director, and ended up as an area electrical and gas supervisor with an electrical utility company for 31+ years.  He saw too many examples of wire nuts and poor quality tape failing over time. So all connections "here" were the more permanent Buchanan splice caps covered with Scotch brand electrical tape.Have taken connections apart that are 30 years old or older and tape is still flexible not all hard and cracked like the cheapo stuff.

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