Primefaces set header for parent component

I am using PrimeFaces 5.1 with JSF in my college project.I try dataTable inside another dataTable.Now I want inside dataTable header to set parent component header.

<p:dataTable value=#{stud.studDetails} var="details">
<p:column>
<h:ouputText value={details.name}/>
</p:column>
<p:column colspan="3">
<p:dataTable value=#{details.subDetails} var="sub">
<p:column headerText="subject">
<h:ouputText value="#{sub.subject}"/>
</p:column>
<p:column headerText="Value">
<h:ouputText value="#{sub.value}"/>
</p:column>
<p:column headerText="Description">
<h:ouputText value="#{sub.descirption}"/>
</p:column>
</p:dataTable>
</p:column>
</p:dataTable>

I need to inside datTable header to set parent datTable header.

Note:

• I try to adjust style to parent header component.If the inside dataTable header increase to outside alignment changed.
• I try ui:repeat and p:dataGrid but facet header but it not working.

If any other way to set inside column header for parent header.