I didn't do this but learned it from http://forum.xda-developers.com/showthread.php?t=1642006 and D2dyno work. I only adapated it to work on the AN 7 G3 As usual I'm not responsible if you brick your tablet. Only know tha it worked great on mine and now have Internal Sd Storage of 32 gig with an Ext Sd of 2.12 gig. I would read D2dyno link very well before you try it and then do what I will show you to change on the AN 7 G3. Also before you do ANY changes, you should have all apks installed or moved back to the tablet or you will have to reinstall those apks left moved to the sd card. Also copy all files and folders on the internal sd card storage to your External Sd Card, this will keep things from not working correctly as you will see happen to one person on D2dyno's comments.

   OK now if you have read D2dyno's Post and think your ready heres what you ned to do for the AN 7 G3....

 Have an Explorer like Root Exployer or ES File Explorer (I used ES File Explorer) and make your you have R/W permissions set in explorer settings. Now go to the tablet root and /system/ect/ and look for this file "vold.fstab", copy this file and save somewhere safe like your micro sd card, then open the file on /system/ect/ with the explorer text editor and go down to these two lines

sdcard /mnt/sdcard auto /devices/virtual/block/nandi dev_mount 

extsd /mnt/extsd auto /devices/platform/sunxi-mmc.1/mmc_host

 

Change these two lines to look like below, all you will change is  sdcard and extsd.....THAT IS ALL, make sure to change nothing else and to also have the same space between everything

 

sdcard /mnt/extsd auto /devices/virtual/block/nandi dev_mount 

extsd /mnt/sdcard auto /devices/platform/sunxi-mmc.1/mmc_host

After changing sdcard and extsd close file editor and it should say changes saved, I still opened the file backup and made sure that the changes were saved. If Explorer File Editor says NOT SAVED then you DO NOT HAVE R/W set in Eplorer and must start over.

 If all is changed and looks good the shut down your tablet and the start tablet back up, mine took a little longer to boot the first time so don't get excited. Now look in tablet settings under Storage and you should see your mirco sd card as Internal Storage and the tablets as EXTSD.

 Save the copy of original file somewhere safe and a copy of the file that you editited. To change back all you have to do is replace that file with the copy and reboot to be back as original, then replace  with the altered file and reboot to be back at Miroc sd card st to Internal Storage.

  Hope this helps someone.