Updating a lookup field from another lookup field

Hello,

I have a PR Conversion object that is related to the Account object. On the PR Conversion I have a couple of lookup fields that are related to the User called Conversion Coordinator and Conversion Sales Rep. The relationship cardinality is Many PR Conversions to One User for both lookup fields. What I would like to do is update the lookup fields of the same type on the Account object to be equal to the lookup fields on the PR Conversion object. 

I have tried numerous attempts to trigger the results using an update trigger:

if({!R45170908.R45173133#id} !== '') {
rbv_api.setFieldValue("account", {!id}, "R55057123", {!R45170908.R45173133#id})
} else {
return ' '
}

and an Object Script trigger:

var x = new Array();
x["R55057123"]="{!R45170908.R45173133#id}";

var newId = rbv_api.updateRecord("account", {!id}, x);

rbv_api.print("Updated record with id: "+newId)

Neither one seems to be working and I thought this would be relatively easy. 

What I am trying to do is I have an email trigger that send an email to the Conversion Coordinator and the Conversion Sales Rep notifying them that a new Follow Up was created on the Follow Up object that is also related to the Account object - One Follow Up to One Account.

I hope I have explained this properly and I appreciate any help with direction and scripting examples.

Thanks :)