On my last boat I had a similar problem. If you initially make the awning as though the boat had no inner forestay, then cut the awning through the centre from the bow end to just aft of where the inner stay will be when the awning is in place. Sew on a separate 4" flap to cover the slit, and use extra wide velcro (or two strips of sewn in standard velcro, side by side) to close the flap. There are many photos on the net showing awnings suitable for traditional sloops..just google 'foredeck awning'. Here's a nifty one to suit a Hanse, and which could be adapted as described as above. Foredeck Awning - myHanse - Hanse Yachts Owners Forum
My last boat was quite large and I had a lot of space for storage. Consequently I made two foredeck awnings from the same homemade pattern. One from 90% beige shadecloth, one from vinyl for the rain.
Best of luck.