Am pretty sure it is. Just log into the page/group where you want to share the post, then find the post you like to share by using the search bar of Facebook to get into the page where the post is going to be shared from. Then click on the post, after that click share, you will find some options, click on write post, because if you select share on the options what will happen is that it will share it to your friends not to your page/group. When you are writing the post on top it will appear an option where you can change where to share that post, so you select you page/group