Yes, it is possible to combine SD card storage and storage on a Fire 7 tablet. Here are some steps you can take to accomplish this goal:
Purchase an SD card that is compatible with your Fire 7 tablet. You will need to make sure that the card is certified for use with Fire OS, which means that the card has been tested and validated by Amazon. Once you have the card, insert it into the slot on your tablet.
Open the storage settings on your Fire 7 tablet. This can be found in the settings menu. Once you are there, you will be able to see the storage options available and select the one that will allow you to switch between internal storage and the SD card.
You can now choose to transfer some or all of your files to the SD card. This can be done by simply selecting the files you want to transfer, and then tapping the "Move" option. Once the files have been transferred, you can view them directly from the SD card.
Using an SD card will provide you with an additional storage option for your Fire 7 table, which can help you free up some space and make it easier to access your files.
If you need more help on this topic, please visit Amazon's official website for instructions on how to move files from internal storage to an SD card.