Quote from Martin Schweiger on November 3, 2021, 4:45 pm

1. Yes, you can claim a foreign priority from a registered design application in a utility model application:

Paris Convention Art 4E(1) says:
"Where an industrial design is filed in a country by virtue of a right of priority based on the filing of a utility model, the period of priority shall be the same as that fixed for industrial designs."

Art 4C(1) says:
"The periods of priority referred to above shall be ... six months for industrial designs ..."

https://wipolex.wipo.int/en/text/288514

2. No, this does NOT work the other way round. The Paris Convention is silent on that aspect. That means that you cannot claim a foreign priority from a utility model application in a registered design application.

3. Yes. A US design patent application may claim priority to a pending utility non-provisional US patent application, but not to a US provisional patent application (see 35 USC § 172, and MPEP 1504.20). And a US non-provisional utility patent application can also claim priority to a US design patent application.