Cannot create custom field for ForumPost Type

Hi, My Sitefinity version is 8.1.5800. I am trying to create a new custom field for ForumPost Type. I have tried the same for ForumThread & ForumGroup Type and succeeded in it but cannot create for ForumPost. I have referred to the below articles as well.

https://www.progress.com/documentation/sitefinity-cms/for-developers-create-custom-fields

https://knowledgebase.progress.com/articles/Article/how-to-create-a-custom-field-for-forum-threads?q=add+custom+field+in+forum+thread&l=en_US&c=Product_Group%3ASitefinity&fs=Search&pn=1

Please note: While executing below code, I am getting some results but there isn't any column created in ForumPost database table i.e. sf_forum_posts table. On the other end, columns are created in database tables related to ForumThread & ForumGroup (sf_forum_threads & sf_forum_groups respectively).

var metadataManager = MetadataManager.GetManager();
var metaPostField = metadataManager.GetMetafields().FirstOrDefault(t => t.FieldName == "like_count");

Can anyone please help me for this?

Thanks in advance