Choosing the license - CC0 BSD or Dual [ seeking advise ]

[lorenzo <plorenzo@disroot.org>]

Dear mentors,

I'm going to add ~20 service runscripts from my collection to a Debian
package that I want to reintroduce in Debian, and I have to chose the
license.
For this project I mainly care about two things:

1. allow fast circulation (even if it's at cost of less protection)

2. make it easy for an upstream project to incorporate a runscript

The original Debian package is under BSD-3Clause, which I think it's
fine for 1., but not sure for 2.
Am I correct that, if I choose CC0/Public Domain, an upstream project
can incorporate the runscript "as is" and change the license without
asking for my permission?
What about dual license -- something like "BSD-3Clause OR
Service Upstream license" ?

Lorenzo