Mike Zingman - N4IRR
You can upload any DMR database to the DVSM app by using the dvswitch.sh script. The script has several commands that will aid you in this process including the download of the database from the internet, processing of that data into a form compatible with DVSM and upload of the processed file to the app.
As to you desire to customize the database. You can change it any way you want before you upload it. One of the best way to customize it is to place your favorite talk groups in the first 10 locations of the file. These first 10 locations are used as the "long press" dial macros you use on the keypad. So, if you want your TG to be number five, place it in the fifth location and when you long press the 5 key on the keyboard it will automatically dial your favorite TG.
Hope this helps,