I would like to use the values of a multi-value field of one record the select options of another record's multi-select picklist. I am currently doing something very similar to this with a query which is returning field values from multiple records in a relationship. 

Here is my current code which pulls the value from a single field from several records : 

public class MycontrollerSFDCBETA2b
{
private final Contract_Overview__c contract;
public String rightOptionsHidden { get; set; }
public String leftOptionsHidden { get; set; }
public String selectedMulPickKeyTech{get;set;} 
public string names{get;set;}
public string accountid{get;set;}
public String message { get; set; }
public List<SelectOption> options { get; set; }
public List<SelectOption> selectedSubs2 { get; set; }
    
    public MycontrollerSFDCBETA2b(apexpages.standardcontroller controller)
        {
        this.contract = (Contract_Overview__c) controller.getRecord();
        }

    public pageReference  execute()
        {
        return null;
        }

    public list<selectoption> getitems()
        {
        accountid=contract.Account__c;
        
        selectedMulPickKeyTech=contract.Subsidiaries_On_Contract__c;
        selectedMulPickKeyTech=selectedMulPickKeyTech.replace('[','');                
        selectedMulPickKeyTech=selectedMulPickKeyTech.replace(']','');

        String[] selectedvalues = selectedMulPickKeyTech.split(',');
        selectedSubs2 = new list<SelectOption>();
        for (String selectedvalue: selectedvalues) 
            {
            selectedSubs2.add(new SelectOption(selectedvalue,selectedvalue));
            }
    
        List<selectoption> options= new list<selectoption>();
            if(accountid != null)
            {
            account a =[select name , (select name from Subsidiaries_and_Brands__r) from account where id =:accountid];
                for(SubsidiariesAndBrands__c s : a.Subsidiaries_and_Brands__r)
                    {
                    options.add(new SelectOption(s.name,s.name));
                    }
            }
            else
            options.add(new SelectOption('None','None'));
            return options;
        }
    
    public void save()
        {
        message = null ;       
        Boolean first = true;
           for ( SelectOption so : selectedSubs2 ) 
            {
                if (first) 
                    {
                    message = message ;
                    }
                    message = message + ', ' + so.getValue() ;
                    first = false;
            }        
                message = message.removeStart('null, ');
                message = message.normalizeSpace();
                message = '['+message+']';
                contract.Subsidiaries_On_Contract__c=message;
        
        update contract;
                       
        }
}

From that code I am using !items as the select options of a picklist on VF. 

I'd like to accomplish the same thing by querying a single record's multi-value field. I have a very VERY generalized idea how to accomplish it. I think I need to take some kind of approach like this : 

String[] picklistlines =new String[]{};
String selectedMulPickKeyTech{get;set;} 

public string contractid{get;set;}

public list<selectoption> getitems()
            {
            contractid=contract.Contract_Title__c;

contract = [SELECT Subsidiaries_On_Contract__c FROM Contract_Overview__c where Contract_Overview__c.id=:contractid];

selectedMulPickKeyTech=contract.Subsidiaries_On_Contract__c;


					
picklistlines = selectedMulPickKeyTech.split('\n');

But I don't know how to properly build the list with the For statement. I also don't think that query will work properly.

If you can give me any help I would really appreciate it. I feel like I'm very close to the solution here.

Thank you very much.