Is there any way to Import Activity IDs Values?

yes 

setup the columns that you want create 1 new activity in p6

right click and select export to excel 

use this a your template to populate new activities any column with and asterisks * in ti CAN NOT be imported

populate the spreadsheet save file in excel 

import into p6 

done 

I did that and populated the Excel with the new values hoping it would have imported the new values to the Activity ID in P6 but it gave an error for each one that it was not a valid Activity ID value.

look at the excel file the activity ID CAN NOT BE a FORMULA also each activity ID begins with a ' this makes it text so if you export the activity A1000 and looked at the cell it would look like 'A1000. Or if it was activity 1000 it would really be '1000 when you look inside of the cell. Follow this format and do not use formulas or move anything around after your export the existing activity to excel as your template. 

Zoltan 

Activity ID(task_code) cannot be updated directly by using the excel update function, as it is the unique identifier that P6 uses to recognize where to update everything else.

Think about it! How P6 will be able to understand which activity updated?

Of coarse there is a Task_ID identifier which is never imports or exports in a conventional excel options. You can use it and change Activity ID (task_code) if you know how to use SDK, API or even directly manipulate XER or XML file (XERparserbuilder) but these methods are not for the faint of heart. On top of that in lots of organizations you will not grant access to SDK, API or even able to import and export schedule XER files freely.

But there is a very easy workaround. 

1- Add a TEXT user defined field.

2-Export excel with the userdefined field and other required fields.

3- Enter your new activity ID's in the user defined field.

4- Import excel file to P6.

5- Run a global change to copy user defined field data to the Activity ID

couple of points:

1- make sure the activity ids are unique by using excel conditional formatting or remove duplicate function. 

2- if you are rearranging Activity ID's you might receive the global change error. In that case i would suggest adding something at the begining of all of the activity ID's and after completing the Activity ID changes go back and use replace function to remove that part.

Oh thank you so much that worked. I was able to bring in the multiple Activity Ids.

Tricia glad I could help 

Emad you are wrong I do this all of the time I also have an excel spreadsheet that will aslo import the wbs assignment as well as the predecessor.