Parameter URL Chaining: Project extent overriding other parameters

Use case:

1. I want to open a project using a specific viewer at a specific location at a specific scale
2. I need this to be url based as this will be integrated from another system
3. no workflows as we don't have this skillset in the organisation and the user does not have funding to contract its creation.

I was hoping to be able to use chained parameters (specifically the viewer, center, scale & project parameters) to open a project using a specific viewer at a specific location at a specific scale.

When I chain these parameters, the project parameter (specifically the project's saved extent) overrides the centre and scale parameters. This occurs no matter where in the url I add the project parameter.

Does anyone have any tips on how the project extent can be overridden in this case?

Thanks

Pete