Possible to pass Temp Table between two objects?

You have a couple of options.

One is to use a single instance codeunit. Your temporary variable is stored and manipulated there. This can be difficult to manage; it is only really an option when you have a large amount of data stored in your temp table that you want to pass around.

The other option is to use a "copy constructor" when you pass a temp table by reference between objects, you don't get access to to the records stored in the temp table in the called object. Therefore you need to create a local temp variable, and copy records into/out of it, for use where you need.
In general, this is the better approach.

Finally, you can try using a real table. You will need to add session id as part of the primary key.