How can I lengthen sleeve in ribbed pattern?

[jkr]

Hello:

Could someone please teach me how to add inches to the sleeve of
a ribbed sweater pattern? (Royal Bamboo: Plymouth Yarn - Ribbed Raglan Pullover - my gauge is 6 rows/inch)

I just finished the first inch of "fancy" ribbing on the sleeve (69 sts):

Row 1: P1, *K1 tbl, P1, rpt from * to end of row.
Row 2: K1, *P1 tbl, K1, rpt from * to end.

On the last row the pattern says to increase 3 sts on K row (72 sts).

Now, I want to add three inches to the following rib pattern before beginning to shape raglans:

Row 1: (RS): K2, *P2, K4. Rpt. from * across to last 4 sts. End P2, K2.
Row2: (WS): P2, *K2, P4. Rpt. from * across to last 4 sts, end K2, P2.

To Shape Raglans: Keeping pat as est, BO 2 sts at beg of next 2 rows (68 sts).

Before I begin to shape raglans, how do I increase the length without throwing the stitch count off when I begin to shape the raglans? Won't I have to add more than the 3 sts I added at the beginning in order for the sleeve to be shaped properly as I increase the length? If so, how/where do I increase in the ribbed sleeve pattern and how/where do I decrease in ribbed pattern when I begin to shape the raglan so I end up with 68 sts (in the first two rows of shaping) so I can continue per the original pattern?

Thank you.