HI....
I am Katsuki and I am quite experienced coder.
About this job, I need more additional information:
1. Are you using Linnworks desktop?
2. About "adding item to order", Do you mean adding from open order to processed order? Sorry I don't quite understand.
3, It would be more helpful if there is a sample data.
I hope you would accept my bid.
Thank you,
Katsuki