The trick to maintaining body contact is making sure that your center is always pointed towards your partner (slight exception in PP, but more on this later). This presents an interesting challenge in O.P. position: One would assume that if you are to shift the tracks of your feet to move outide, you would therefore also shift your entire body over, too. But this is not in fact the case.
Rather than "shifting" your relative body positions to the left or right, you will actually rotate your bodies to an angle which is different from the feet (or rotate the feet to an angle different than the bodies, depending on context). This opens up a narrow corridor for your foot and lower leg to slip through without having to shift the bodies over.
To demonstrate this point, try standing in dance position facing line of dance and turn both of your feet 45 degrees to the left (pointing diag center). Your partner should also turn his or her feet 45 degrees to the left (pointing DW against LOD). Do not turn your bodies; only your feet. Walk forward towards diagonal center, first with your left foot, and then with your right. The right foot should be placed along the same track as the left. Notice that because your bodies did not rotate, you can still maintain body contact. But because your feet did rotate to an angle different than the body, you created a narrow corridor just wide enough to slip your right foot and lower leg O.P.
You could achieve the same effect by beginning facing diagonal center, and turning your body 1/8 to the right to face line of dance, while still leaving your foot pointing DC. Naturally, your partner would do likewise, ending with the body backing LOD and feet pointing DW against LOD. This time you turned the bodies rather than the feet, but the end result was the same.
When dancing a Feather step, it's important to remember that the bodies of both man and lady must rotate over the feet in order to create the narrow corridor necessary to move O.P. Without this rotation, you are forced to shift the bodies over, which puts strain on the dance position and minimizes body contact. It also makes it more difficult to re-adjust to the following step which is taken in-line.
Promenade position is different in the sense that your bodies do not face each other entirely. It is necessary to turn the hips into a "V" shape. But again, body contact is only possible when the feet are turned to an angle different that the body.
Assuming that you cannot rotate your top-line oppositionally to your partner's (this would break one or both top-lines), the only other option you have is to have your lower and upper body at different angles. So think of promenade as being parallel in the toplines, with the hips turned into a V-shape and the feet turned more (some would even say parallel to the top-line).
A few more things to remember about PP as a lady:
(1) In closed position, you have a right front to right front connection. When you turn from this position to PP, it should leave you with your center line to his right front.
(2) In closed position, you are dancing in front of the man's right front. In PP, this means that your position is slightly *behind* the man. Do not try to step past him on step 2 on your left foot; Keep that left leg slightly behind his right.
I hope this helps!
Sincerely,
Jonathan Atkinson www.ballroomdancers.com