5 hour baby sweater for an 18 month old

I am interested in trying the 5 hr baby sweater as my first try at knitting something other than a scarf, but my twins won’t fit the 6 month size that the pattern is for. Does anyone know where I can find a pattern it in 18 month size or how I can size this pattern to fit a bigger baby?

You can add another increase row or two, following the inc pattern that’s already established. So the last inc rows are -
[FONT=Arial,Helvetica][SIZE=-1]Row 28: Knit, increasing 1 st at each side of markers (119 sts)[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Row 29: Same as row 27.[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Row 30: Same as row 28. (127 sts)[/SIZE][/FONT]
[FONT=Arial,Helvetica][SIZE=-1]Row 31: K3, P to last 3 sts, K3[/SIZE][/FONT]

Do a couple more until the width of the knitting is about the chest size you want for the sweater. Then, since you’ve increased 8 sts per extra inc round, do the dividing row. Each extra 8 sts will be 1 on the R front, 2 on R sleeve, 2 on the back, 2 on the L sleeve and 1 on the L front, so you’ll know how many extra for each section when you go to divide them up.

Thanks. This is my first time knitting anything other than a scarf so I’m sure that I will have plenty of other questions along the way, but I am looking forward to starting.

heres the pattern i use. It will fit a variety of sizes. Check it out.