An alternative to using the multi-picture post type for including more than one picture in your post, is to use an album link post. This will use a link to a photo album on a business page or public persons page or a group*. Once your post applies to your destination (page or group), all the photos on that album will show up in a beautiful slide show!
*You should use a public group to create an album  if you want to be able to use this link in different destinations, i.e. in templates for multiple parties, etc. If you create an album link in a closed or secret group, only members that have joined that same group will be able to see the pictures, otherwise they will see “Attachment Unavailable” (NOTE: if some guests are not able to see pictures that you post, it’s possible that they are still in “preview mode”)

Here's how to get started: 

1. Go to your destination (Facebook business page, public person's page, or group) and create a photo album by uploading photos, and giving it a name and optional descriptions. (The pictures in this tutorial are from a FB Business Page)

You can also choose to hide it from your timeline if you don't want it shown there until you are ready to post it. It will post in the order shown so be sure to drag and drop to change the order if you have a specific one in mind.

2. Next, copy the destination link. From a group album, use the browser link. From a page, click the “...” button to the right of the album title, and click “Get Link”.**

**NOTE: If for some reason you don't have the option to "Get Link", you can use the browser link from the URL box at the top of the page, and select a website post type when creating the post - it should still display it the same way in FB.
 
3. Paste into the link URL field of the Album Link post you are creating in PostMyParty.

4. Sit back and watch it post!

Happy posting!