I tried but This also save other folders without any content
Only folders are saved no content under Sub1/*-
*.* !/.BackupIgnore* !/SubFolder_to_The_SisterFolder_To_IgnoreFile/Sub1/ <---- For folder !/SubFolder_to_The_SisterFolder_To_IgnoreFile/Sub1/* <---- For content
Please provide a tree structure of your source starting from root you use for your snapshot. Then indicate what you want to exclude/include and we can try to work out how to do it.
Giving only some partial information makes it impossible to help.