How can you move images between collection “A” and collection “B” on an IOS device using LR Mobile? ON the PC I simply drag and drop the images
Open Collection on Lightroom Mobile, Click on the arrow on the top right side corner and select the option "Move To" and select the images you want to move to another collections. Once you done selecting images, click on the arrow again on the top right hand side corner and then select the collection where you want to move them.
You refer the below video link for step by step instructions.
Let us know if that helps.
Perfect. Thank you!