Pattern instructions help needed - a sleeve


I’m a relatively novice knitter, but knitting something complex (an Aran jersey) but doing ok until I hit the sleeve. Having completed 20 rows (as per the pattern) which involved increasing a stitch at either end of a number of the rows. These 20 rows create the Aran pattern. In order to continue with the sleeve, the pattern says the following:

From 1st to 20th row sets rice-st, cable panels and diamond patt. Keeping continuity of patt as set (throughout) inc 1 st at each end of 3rd and every foll 6th row to 87 sts, working inc sts in rice-st.

Does this mean that I continue with the pattern and only inc. stitches at the ends of the the 3rd and 6th rows, or is this rows 3rd, 6th, 9th, 12th, 15th and 18th rows?

Also, in addition to the inc. stitches at the ends of the 3rd and 6th rows, do I still increase stitches as per the pattern for first 1-20 rows, e.g. 5th row K1, m1p, k1, (p1,k1) 2 times …

Rather confusing. I would greatly appreciate someones help!

Many thanks,

The sleeve increases are at the ends of the 3rd row and then every 6th row. So if you increase on row 3, the following increases would be on 9,15,21,27,etc until you have 87sts.
If the m1p is part of the pattern stitch on the sleeve, then continue with that increase. Is there a decrease in the patten stitch also?