How to Shift cells of a grid (regarding TileMap)

I am trying to make a game and the game i need to be able to place various objects in a grid.

Since my team decided to use Unity 2D TileMap i tried to do this with the built in Grid component but it doesnt really seem to work the way i need.

So this is how grid looks like .

But what i need is the following grid .

As you can see there cells are shifted to the Y axis half way.

What i have tried with the built in grid.

• Copy the original tilemap and move the position to make it 'shifted' . (comes with a problem since there are two tilemaps)

• Copy the grid and move the position . (grid looks shifted but the object placed on the tilemap looks the same)

And i searched for possibility to customize Unity built in grid but it doesnt look possible so Anybody has any idea?? Thanks .