This tip is a must have when developing websites in Kentico's portal engine.
Since version 5.5 it is possible to setup multiple placeholders in your page templates. Simply follow the two steps below:
1. On the parent page template (i.e. Master template) add a "Page placeholder" web part
2. Add the following code in the child page template (i.e. Default template). Make sure the PagePlaceholderID matches with the Web part control ID of the Page placeholder from step 1.
<cms:CMSContent runat="server" id="cntContent" PagePlaceholderID="plcContent">
<cc1:CMSWebPartZone ID="zoneContent" runat="server" />
</cms:CMSContent>
For more information on this tip check out the excellent post by Kentico's CTO Martin Hejtmanek:
Using multiple page placeholders in Portal engine