Out of interest I made a quick test in my Innovator 12.

I added a foreign property "test" in Manufacturer Part to link a property from Manufacturer to Manufacturer Part.

Then I added a foreign property in Part AML to link the "test" property from Manufacturer Part into "Part AML". This one worked for me!

Is the property in Manufacturer a List Data Type?

If I use nash, I can retrieve the correct value of prop1, but in the form, it doesn't show the original List of ItemType "ItemType3"  of the example

I changed it to a list property in Manufacturer and it worked too!

See here:

List property is linked from Manufacturer to Manufacturer Part to Part AML.

Do you use multilingual extension? Cause when you don´t have translation added sometimes Innovator doesn´t show the right value.

I don't use multilingual extension.

It  is  showed here

but not here

What is your version of Aras?

Ah I see! I can confirm that the dropdown is only shown in the grid, but not in the form. 

And I think I know the reason. The datasource property used for the field links to the wrong ItemType. The detailed settings are unfortunately not visibly in the Form editor.

But "Field" contains a property "Propertytype_id" that links the field to the property. So in my case the property from "Part_AML" is linked, but not the one from "Manufacturer_Part".

I remember I once changed this one inside the SQL database to link the correct itemtype property. But I wouldn´t recommend the solution.

When you able to get the property data via AML, I would use an onLoad/onFormPopulate Method to fill the dropdown on form load.

It´s not hard to do and easier to maintain then manipulating the SQL database.

https://community.aras.com/f/development/3791/add-dropdown-values-programatticaly

Ah I see! I can confirm that the dropdown is only shown in the grid, but not in the form. 

And I think I know the reason. The datasource property used for the field links to the wrong ItemType. The detailed settings are unfortunately not visibly in the Form editor.

But "Field" contains a property "Propertytype_id" that links the field to the property. So in my case the property from "Part_AML" is linked, but not the one from "Manufacturer_Part".

I remember I once changed this one inside the SQL database to link the correct itemtype property. But I wouldn´t recommend the solution.

When you able to get the property data via AML, I would use an onLoad/onFormPopulate Method to fill the dropdown on form load.

It´s not hard to do and easier to maintain then manipulating the SQL database.

https://community.aras.com/f/development/3791/add-dropdown-values-programatticaly

Ok, thank you very much, I'll try to add programmatically the values. But I don't kown why in Aras 10 it runs correctly

It could be possible that I miss something. If you have a subscription, ask Aras if this feature is something that has changed since Innovator 10.

I've asked Aras for information and they have confirmed that lists do not persist through foreing property relationships. I have to modify my itemtype.

I've simply resolved adding an hidden List1 property in the itemtype1.