Hi @Paulcofla
See the demo flow which helps to add attachments to a new list from existing list when item is created /Modfied.
Assume we have two list - List12 and List13. The requirement is when item is created/Modified in List12 , item should be created/Modified in List13 respectively This flow would be with respect to attachments.
see below
1. use trigger

2. use get attachments to get all attachments from a list item in list 12

3. Get items from List13 corresponding to item created/modifed in List12 if available.

(Here title is my unique identifier)
4. Use condition to check whether the items are present as output from get items

Expression -
length(outputs('Get_items')?['body/value'])
If condition is True-
Then item is created in List13 and attachments are also added from item in List12 to List13.
if condition is False-
in No branch do the following
a. use get attachments to get details of attachments from List13
Expression to get id - first(outputs('Get_items')?['body/value'])?['ID']
b. use apply to each to loop output of attachments obtained from get attachments details from List12.
Within the loop try like below
b1- use filter array to check whether item in List12 is present in List13 or not ?
b2. write a condition like this to check output of filter has zero elements or not?
Expression - length(body('Filter_array'))
If condition is satisifed- follow the actions in Yes branch-
Next use add attachment to attachment not present in List13
Expression - first(outputs('Get_items')?['body/value'])?['ID']
This is the design---
Hope this helps !