Can I do this?

I finally found a sweater pattern that my DH likes! I was all set to order yarn and realized that the pattern is a DK weight!!! I wanted to use WOTA yarn from knit picks. Is it possible to make that adjustment on a pattern? Also the DK weight yarn on KP (50 gm/123 yds) is a LOT different yardage than the DK weight yarn that is recommended in the pattern. (100gm/348 yd) How does that work?

Well have a look at the gauge that is recomended in the pattern and the gauge for WOTA ( i don’t know that yarn myself so im not sure how it compares to a DK weight).
If the gauge is only slightly different you may be able deal with it just by using slightly smaller needles (im assuming that WOTA is a heavier yarn). the other alternatie is to do a swatch of the WOTA and see what gauge you get, and how that fits into the measurements of the sweater. You may be able to alter the pattern so you are just casting on a different number of stitches to accomodate the bulkiier yarn to give you he same size.

As for yardage, if the pattern called for 5 balls of a yarn that came in 348 yd balls, then it is actually calling for 1740 yds of yarn. If the yarn you want comes in 123 yd balls then you would do 1740/123 =14.15 or rounded up 15 balls of yarn

Thank you! But why is their such a difference in yardage between the KP and the other if it is the same weight of yarn?

You could knit a smaller size using the worsted. KPs DK (merino style) is really not much thinner than WoTA, about the same really, so that’s why it has less yardage than a `real’ DK.

yarns can vary an awful lot within a weight category, it will also depend on what type of fibre is used. Also don’ forget that the KP yarn s in 50g balls rather than 100g balls so you will get less yardage per ball.