Insulation, Radiant and Vapor Barriers - Insulation between irregularly spaced joists

I am insulating the ceiling in a bedroom. Joists vary between 17 and 24 inches. What is the best way to splice strips of kraft-faced 15" fiberglass into the space. For example, should I cut a strip a few inches wide and tape it to the other strip, using staples on both joist faces? I have heard about insulation screen or mesh that can hold insulation in, could that help?

Since you're using kraft-faced insulation, I am assuming that there is unheated attic space above the bedroom. Can you lay the insulation in from above?
If it were me (and this isn't the only way), I would slice the insulation length-wise with 1/2" more total width than each space, and lay it in beside the 15" (flaps down).
Use a straight edge, like an 8' 2X4, and a sharp utility knife, to cut the insulation.
You can compress it to cut it, but compress it as little as possible when installing.
If you can put it in fairly easily from above, I would use unfaced insulation with plastic sheeting stapled on the bedroom ceiling to hold it up (stapled in place first).
If not, install the kraft insulation without taping the seams, and staple the plastic up as you go.
This will give you a better, solid vapor barrier, and save taping and other work.
Good Luck!
Mike