I love it too and will order the pattern this weekend! Not having seen the instructions in the pattern yet, I have some tips for "Y" seams. I used to make lone star tops for a living and got to be well practiced at this.
Mark the the tips of your inset pieces with 1/4 inch sewing lines , not the whole piece...just the tips. Where the lines come together to form an "X" stick a straight pin in the center of the "X". Now mark the diamonds in the same way where the seam of the diamonds come together. Placing right sides together on one side stick the straight pin through the "X" mark on the diamonds and then stick the pin through the diamond pieces as well. Now push the pin the rest of the way into the fabric to keep the fabric and pin from moving. Sew from the crotch of the diamonds where the pin is located down one side all the way to the end of the inset piece. Next sew the other side the same way. When you do this you have to maneuver the fabric of the inset a little to get it to line up in a straight line so you can sew the seam. The pin being in place gives you a little fulcrum to pivot on so things stay in place at the corner where it all comes together. Hope this is of some help to you.
Wanted to add that the Lone Star has five points, the Bethlehem Star has eight points. I love this star with six points and the difference in the look because of the small diamonds within.