user11036: I want to merge two comps in after effects so, when I play contents from both layers shows.
At the current time the upper composition dont allow the lower composition to display its contents.

user10866: If you mean that you have two compositions in one main composition, and you want both to show their contents on top of each other, then I can help you.
Make sure that you click on "Toggle Switches / Modes",

so that you have the "Mode" option available.

Now set the top composition to either "Screen", "Add", or "Lighten".

Make sure that the top composition has at least some transparent part in it, if it's just a full solid black layer, nothing's going to show through be default, unless you lower the opacity down.

11036: <p>I want to merge two comps in after effects so, when I play contents from both layers shows.</p>

<p>At the current time the upper composition dont allow the lower composition to display its contents.</p>
 10866: <p>If you mean that you have two compositions in one main composition, and you want both to show their contents on <strong>top</strong> of each other, then I can help you.</p>

<p>Make sure that you click on "Toggle Switches / Modes",</p>

<p><img src="https://i.stack.imgur.com/92Bco.png" alt="enter image description here"></p>

<p>so that you have the "Mode" option available.</p>

<p><img src="https://i.stack.imgur.com/51fnT.png" alt="enter image description here"></p>

<p>Now set the top composition to either "Screen", "Add", or "Lighten".</p>

<p><img src="https://i.stack.imgur.com/Ljtpp.png" alt="enter image description here"></p>

<p>Make sure that the top composition has at least some transparent part in it, if it's just a full solid black layer, nothing's going to show through be default, unless you lower the opacity down.</p>
