Understanding Annotation in Altium

Use case:
hierarchical design and design reuse.
Using DeviceSheet_A, DeviceSheet_B, DeviceSheet_C in top level TitleSheet1.

Designators in
DeviceSheet_A: U1, R1, R2, R3
DeviceSheet_C: U1, U2, R1, C1,C2, D1, D2, R3
DeviceSheet_B: U2, R1, R2, R3

Issue:
Error in Compile:
Issue with U1, U2, R1, R2, R3 as the Designator is Duplicate.

Question:
How do you annotate this? which style? any help appreciated
(tried, but failing)

(Not having issue with Multi-channel as the Designators get amended, so lets not go to multi-channel)
Solution
No two part can have same designators,
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