I would trim the three wires back - bare them all - twist the three together - tin them well - trim the "daggy" bit off the end then solder the finished "group" to the tag.
Slow but correct and will minimise any future issues with wires falling off tags etc.
+1
That's the only way to do it.
Make sure the soldering tip is clean and tin the tip with a little bit of solder. Use needle nose pliers to hold the twisted three wires together while soldering to the lugs. There is no "fast" way of doing this. It has to be done properly to avoid issues.
