Yardage

I'm going to be knitting an animal hoodie.  The client suggests size 10-15 months.  I have the actual pattern, and the size choices are 6-9 month and 12-18 months.  I guess 9-12 month olds wouldn't wear this?  Anyway, the yarn requirement for 6-9 months is 108yds.  It's mainly in one colours, with a small amount in a second colours (inside the ears).  The recommended yarn, that I'm using, is 106yds per ball.  Ugh.  The 12-18 month size takes 125yds.  Even trying to resize in between these won't make it a one ball project.  I have ONE ball.  I can get more, but not necessarily the same dyelot.  Ugh.  These animal hoodies seem really popular, so hopefully I'll get more orders for the light cream version....