My head is whirling with this - I have read the docs, the boards and everything else, but until I get more experienced, I'm really grateful for the help.

Here is the latest code:

<apex:page standardController="Call_Meeting_Report__c" extensions="ReportSearchController" showHeader="true" sidebar="true" action="{!loadDefaults}"> <apex:form > <apex:pageBlock title="Call/Meeting Report" mode="edit" id="thePageBlock"> <apex:pageMessages /> <apex:pageBlockButtons > <apex:commandButton value="Save" action="{!save}"/> <apex:commandButton value="Cancel" action="{!cancel}" immediate="true"/> </apex:pageBlockButtons> <apex:pageBlockSection columns="2"> <apex:inputField value="{!Call_Meeting_Report__c.Account__c}" > <apex:actionSupport event="onChange" action="{!getDetails}" rerender="ChOpp, ChCon" /> <apex:actionSupport event="onkeyup" action="{!getDetails}" rerender="ChOpp, ChCon"/> <apex:actionSupport event="onclick" action="{!getDetails}" rerender="ChOpp, ChCon"/> </apex:inputField> <apex:pageBlockSectionItem id="ChOpp"> <apex:outputLabel value="Opportunity "/> <apex:selectList value="{!Call_Meeting_Report__c.Opportunity__c}" id="opps" size="1"> <apex:selectOptions value="{!Opps}"/> </apex:selectList> </apex:pageBlockSectionItem> <p/> <apex:pageBlockSectionItem id="ChCon"> <apex:outputLabel value="Contact "/> <apex:selectList value="{!Call_Meeting_Report__c.Primary_Contact__c}" id="conts" size="1"> <apex:selectOptions value="{!Conts}"/> </apex:selectList> </apex:pageBlockSectionItem> <p/> <apex:inputField value="{!Call_Meeting_Report__c.Date__c}"/> <apex:inputField value="{!Call_Meeting_Report__c.Type__c}"/> <apex:inputField value="{!Call_Meeting_Report__c.Purpose__c}"/> <apex:inputField value="{!Call_Meeting_Report__c.Other_people_present__c}"/> <apex:inputField value="{!Call_Meeting_Report__c.Discussion__c}"/> <apex:inputField value="{!Call_Meeting_Report__c.Next_actions__c}"/> <apex:pageBlockSectionItem /> </apex:pageBlockSection> </apex:pageBlock> </apex:form> </apex:page>

 I'm busy trying to extend the controller so that the page will work whether invoked from an account, opportunity or contact, so it is a work in progress, but the part relating to this discussion works.

public with sharing class ReportSearchController { //add an instance variable for the standard controller private ApexPages.StandardController controller {get; set;} // the actual call/meeting report private Call_Meeting_Report__c cmr {get; set;} private Id a, newa, OppThere, ContThere; public List <selectOption> Opps {get; set;} public List <selectOption> Conts {get; set;} // Initialise the controller public ReportSearchController(ApexPages.StandardController controller) { //initialise the standard controller this.controller = controller; cmr = (Call_Meeting_Report__c)controller.getRecord(); //this.a = (Account)controller.getRecord(); } // the results from the search public PageReference getDetails() { List <selectOption> NewOpps = new List<selectOption>(); List <selectOption> NewConts = new List<selectOption>(); newa = cmr.Account__c; system.debug('### Old Account is '+a+' New Account is '+newa); if ((newa != a)&&(newa != null)){ // Don't want to make SOQL call if we don't need to // use some dynamic soql to find the related opportunities by name try { List <Opportunity> opplist = [Select Id, Name from Opportunity Where AccountId = :newa Order By Name]; for (Opportunity o:opplist) { NewOpps.add(new selectOption(o.Id, o.Name)); system.debug('### NewOpps option added -'+o.Name); } List <Contact> contlist = [Select Id, Name from Contact Where AccountId = :newa Order By Name]; for (Contact c:contlist) { NewConts.add(new selectOption(c.Id, c.Name)); system.debug('### NewConts option added -'+c.Name); } } catch (Exception e) { System.debug('### error '+e); ApexPages.addMessages(e); } // Opps = NewOpps; Opps.clear(); Opps.addAll(NewOpps); Conts.clear(); Conts.addAll(NewConts); } else if (newa == null) { Opps.clear(); system.debug('### Emptied Opps & Conts lists'); Conts.clear(); } return null; } public void loadDefaults() { Opps = new List<selectOption>(); Conts = new List<selectOption>(); String Opp1, Cont1; a = cmr.Account__c; OppThere = cmr.Opportunity__c; ContThere = cmr.Primary_Contact__c; system.debug('### Account is '+a+' Opp is '+OppThere+' Contact is '+ContThere); // use some dynamic soql to find the related opportunities / contacts by account name try { if (OppThere == null){ List <Opportunity> opplist = [Select o.Id, o.Name from Opportunity o Where AccountId = :a Order By o.Name]; for (Opportunity o:opplist) { Opps.add(new selectOption(o.Id, o.Name)); system.debug('### Opp option added -'+o.Name); } } else { List <Call_Meeting_Report__c> cmrlist = [Select c.Opportunity__r.Name, c.Opportunity__c From Call_Meeting_Report__c c where c.Id =:cmr.Id]; //*** Opp1 = cmrlist[0]. system.debug('### Opp already there, adding '+cmr.Opportunity__r.Name); Opps.add(new selectOption(OppThere, cmr.Opportunity__r.Name)); } if (ContThere == null) { List <Contact> contlist = [Select Id, Name from Contact Where AccountId = :a Order By Name]; for (Contact c:contlist) { Conts.add(new selectOption(c.Id, c.Name)); system.debug('### Cont option added -'+c.Name); } } else { Conts.add(new selectOption(contThere, cmr.Primary_Contact__r.Name)); system.debug('### Contact already there, added '+ContThere); } } catch (Exception e) { System.debug('### error '+e); ApexPages.addMessages(e); } } }