Append rows and update data table on a frequent basis


I have two data tables in my project. Table A & Table B. These two tables have the same set of columns.

Table A has the initial data embedded from a csv file. Table B fetches data from info link once in 2 weeks and hence, data of the last 2 weeks will be over-written. I need to auto-append all the rows of Table B to Table A before "B" is refreshed. By this, I will have all the data available in Table A and hence, size of Table A grows every 2 weeks (depending on content Table B). All the visualizations will be based on Table A. 

I have tried "Insert > Row" functionality. But this feature doesn't retain the rows added from Table B before this table is updated/refreshed. Meaning, it doesn't append the rows & retain, instead, it always adds the latest available data in Table B to the Table A.

Could anyone help me with this? Thank you.  



(1) Answer