How to create dynamic dropdown list in relationship grid property

I don´t think dynamic dropdown in relationships are possible right now with regular Innovator Methods. Also dynamic lists (that you then would display in your dropdown) are right now not possible. 

You can use dynamically dropdowns in Forms, but never have seen then in grids.

finally got solution, OnEditStart event the below javascript method will do...

var prop = "name_R" //Rename to your column name _R | Ex: selected_stone_R

var relgrid =  parent.relationships.iframesCollection[parent.relationships.currTabID].contentWindow.grid;

var keys = [];

var values = [];

//=========================

//Add list options here

addOption("key1", "value1")

addOption("key2", "value2")

addOption("key3", "value3")

addOption("key4", "value4")

addOption("key5", "value5")

//=========================

relgrid.columns_Experimental.set(prop, "editType", "FilterComboBox")

relgrid.columns_Experimental.set(prop, "comboList", values, keys)

function addOption(key, value) {

      keys.push(key);

      values.push(value);

}

finally got solution, OnEditStart event the below javascript method will do...

var prop = "name_R" //Rename to your column name _R | Ex: selected_stone_R

var relgrid =  parent.relationships.iframesCollection[parent.relationships.currTabID].contentWindow.grid;

var keys = [];

var values = [];

//=========================

//Add list options here

addOption("key1", "value1")

addOption("key2", "value2")

addOption("key3", "value3")

addOption("key4", "value4")

addOption("key5", "value5")

//=========================

relgrid.columns_Experimental.set(prop, "editType", "FilterComboBox")

relgrid.columns_Experimental.set(prop, "comboList", values, keys)

function addOption(key, value) {

      keys.push(key);

      values.push(value);

}

Wow, congrats! Didn´t expect this one to be possible at all.

Please specify target version of Innovator.
I face similar issue/task and play around of this API (columns_Experimental.set). For Innovator 12 SP6 it is not working. It seems that it was rewritten and part of old methods become obsolete.

I am not able to find solution so far and thinking about to move to solution when popup with available checkboxes will appear on cell edit.

Also please take into mind if API was changed in Innovator 12 and you provide it for Innovator 11 you will decrease upgradeability of your solution.