The plan

When I knit the baby sack, I did not take into consideration that baby doesn't go anywhere without a car seat.  And car seats have buckles.  Buckles that the Baby Sack does not accommodate.  Which meant the baby sack was not be utilized much.

So, taking a clue from Baby's First Entrelac (from Entrée to Entrelac), I decided to add a slit for the car seat buckle.  Baby's First Entrelac uses a three-needle bind off, but I tried out Elizabeth Zimmermann's afterthought pocket, without the pocket.

Of course, I did not try this on the baby sack itself.  Instead, I knit up a sample with some left over acrylic.

The bottom edge of the slit is i-cord bind off.  Once the ends are woven in, the edges will hopefully withstand tugging and pulling.  I think I will give the flap an oval shape.  This slit will be in back, as the car seat buckle should fit between the bottom two buttons on the front just fine.

Now I just need to get up the nerve to snip a stitch on the baby sack to get this going for real.  Cutting into knitting just seems wrong.