I have 2 lists one is a master list and other a shopping list. When I tap on the first, it automatically updates the second. When I tap a button to delete an item from the it should automatically should do the same for the sacond (it does). But when I try to save both lists, it doesn't save either. what am I doing wrong?
Yep, that worked. Both companion and apk. Thank you.
Sorry, I tested your solution both aia and apk but when I adapted it to my project, it didn't work.
It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.
To get an image of your blocks, right click in the Blocks Editor and select "Download Blocks as Image". You might want to use an image editor to crop etc. if required. Then post it here in the community.
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.
Sorry. I deleted the project and tried to start again. Then gave up on it.