Yes, this is possible by having 2 Conditions on your Notes object, and combining them with Condition Logic of “1 OR 2”. The first Condition is Field from another Model, where ParentId = (Account)(Id), the 2nd Condition is Field from another Model where ParentId is one of the Ids of related Contacts for that Account — so you will have to have a 2nd Contacts Model that retrieves Contacts for that Account.

Here’s what your Conditions on the Notes model should look like:

And here’s a screenshot of what an example page would look like. Notice that its showing Notes that are associated to both Genepoint Contacts, as well as for Genepoint itself:

Here is the XML for this sample page:

<skuidpage showsidebar="true" showheader="true" tabtooverride="Account">   <models>

      <model id="Account" limit="1" query="true" createrowifnonefound="false" sobject="Account">

         <fields>

            <field id="Name"/>

            <field id="CreatedDate"/>

         </fields>

         <conditions>

            <condition type="param" enclosevalueinquotes="true" operator="=" field="Id" value="id"/>

         </conditions>

      </model>

      <model id="Contacts" limit="100" query="true" createrowifnonefound="false" sobject="Contact">

         <fields>

            <field id="FirstName"/>

            <field id="LastName"/>

         </fields>

         <conditions>

            <condition type="modelmerge" value="" field="AccountId" operator="=" model="Account" enclosevalueinquotes="true" mergefield="Id" novaluebehavior="noquery"/>

         </conditions>

      </model>

      <model id="Notes" limit="100" query="true" createrowifnonefound="false" sobject="Note">

         <fields>

            <field id="Title"/>

            <field id="Body"/>

            <field id="ParentId"/>

            <field id="Parent.Name"/>

            <field id="OwnerId"/>

            <field id="Owner.Name"/>

         </fields>

         <conditions logic="1 OR 2">

            <condition type="modelmerge" value="" field="ParentId" operator="=" model="Account" enclosevalueinquotes="true" mergefield="Id" novaluebehavior="noquery"/>

            <condition type="modelmerge" value="" field="ParentId" operator="in" model="Contacts" enclosevalueinquotes="true" mergefield="Id" novaluebehavior="deactivate"/>

         </conditions>

      </model>

   </models>

   <components>

      <pagetitle model="Account">

         <maintitle>

            <template>{{Name}}</template>

         </maintitle>

         <subtitle>

            <template>{{Model.label}}</template>

         </subtitle>

         <actions>

            <action type="delete"/>

            <action type="clone"/>

            <action type="share"/>

            <action type="savecancel" window="self"/>

         </actions>

      </pagetitle>

      <basicfieldeditor showsavecancel="false" showheader="true" model="Account" mode="read">

         <columns>

            <column width="50%">

               <sections>

                  <section title="Basics">

                     <fields>

                        <field id="Name"/>

                     </fields>

                  </section>

               </sections>

            </column>

            <column width="50%">

               <sections>

                  <section title="System Info">

                     <fields>

                        <field id="CreatedDate"/>

                     </fields>

                  </section>

               </sections>

            </column>

         </columns>

      </basicfieldeditor>

      <tabset rememberlastusertab="true" defertabrendering="true">

         <tabs>

            <tab name="Contacts">

               <components>

                  <skootable showconditions="true" showsavecancel="true" searchmethod="server" searchbox="true" showexportbuttons="false" pagesize="10" createrecords="true" model="Contacts" buttonposition="" mode="read">

                     <fields>

                        <field id="FirstName"/>

                        <field id="LastName"/>

                     </fields>

                     <rowactions>

                        <action type="edit"/>

                        <action type="delete"/>

                     </rowactions>

                     <massactions usefirstitemasdefault="true">

                        <action type="massupdate"/>

                        <action type="massdelete"/>

                     </massactions>

                     <views>

                        <view type="standard"/>

                     </views>

                  </skootable>

               </components>

            </tab>

            <tab name="Notes" loadlazypanels="true">

               <components>

                  <skootable showconditions="true" showsavecancel="true" searchmethod="server" searchbox="true" showexportbuttons="false" pagesize="10" createrecords="true" model="Notes" buttonposition="" mode="read">

                     <fields>

                        <field id="Title"/>

                        <field id="Body"/>

                        <field id="ParentId"/>

                        <field id="OwnerId"/>

                     </fields>

                     <rowactions>

                        <action type="edit"/>

                        <action type="delete"/>

                     </rowactions>

                     <massactions usefirstitemasdefault="true">

                        <action type="massupdate"/>

                        <action type="massdelete"/>

                     </massactions>

                     <views>

                        <view type="standard"/>

                     </views>

                  </skootable>

               </components>

            </tab>

         </tabs>

      </tabset>

   </components>

   <resources>

      <labels/>

      <css/>

      <javascript/>

   </resources>

</skuidpage>