I have been working on two patterns from Kim Hargreaves book, Echoes. One is completed minus seaming and the other is in the knitting process. It is an openwork pattern and as I began the seaming process, primarily first the shoulder seams, I could not decide how to seam these. Since the pattern has so much open work, I don’t feel that mattress stich would work very well and I am debating between backstitching which I rarely like to do and crocheting but feel the crochet would not be strong enough.
Of course I am going to run into the same problem on all the seams.
The pattern stated to seam the shoulders with back stitch or mattress stitch, but I feel this would not lie flat and may even bunch up with the open holes.
Any suggestions would be greatly appreciated.
Thank you if you can offer any help.

I think it would help to know the names of the patterns so we can see the extent of the openwork. Even though they are from a book, the photos may be online.
I’ve seamed openwork before and as I recall, I usually wind up adding a row of stockinette at the shoulders for a firmer backstitch seam.
At the sides and depending on how open the stitch pattern is, I may backstitch to the open space, knot, seam to the next open space and repeat. If it’s very lacy, I’ve even used thread to seam and hidden the thread in the adjoining pattern to get it across the open space.

Thank you for replying to this question. The patterns that I am working on are Spray and Aqua. Both patterns are in Kim Hargreaves “Echoes.”

I prefer to use the three needle bind off on most shoulders which I may do on the Aqua since it is not completed or
I could possibly make adjustments to the pattern, in adding a row or two of stockinette as you suggested (thanks for that suggestion), when I get to that portion of the pattern. The side seams and sleeves still have me puzzled. It appears to me now, as though I should have added two edge stitches to the sleeves and side seams, so that I could have stitched into them.

The Spray sweater pattern is completed except for assembly and I don’t see anyway of adding rows to this since the back neck extension is included in knitting the shoulder. I am not certain how, but maybe rip out the entire shoulder and redo where the extension is added.
It is beginning to look as though I could rip both sweaters, which I am hesitant to do, as this is tape yarn and it would be difficult to get the same gauge or finished product.

Those are very elegant sweaters.

The Aqua project I linked to does show a column of sts at the side seam.
I wonder if you could either crochet a line of chain sts and single crochet up the side and at the sleeves or crochet the pieces together? The chain stitch could fill in the space between the knit trellises.
Even if you’re not a crocheter there are videos online for these basic sts. I usually follow them if I need to work crochet to finish a knit piece.

That photo shows Aqua and I will have to inspect it, but there is not a row of stitches on Spray. I had thought of trying to use the crochet seaming, but will have to try it to see. I have not crochet much in years, but am sure it would come back once I got the correct hook to use. I did find in my search a shoulder seam stitch that was illustrated on Lana that seems to have worked fairly well for the shoulders. It is not my preferred method but it doesn’t look too bad and did not bunch up as I was concerned with happening.
Thank you so much for taking the time to give me your thoughts. They are most appreciated.