3D reconstruction with several stacks + alignment

Goodmorning everyone! I am struggling with the reconstruction of a 3D image with several stacks. I have 7 series of confocal stacks that I want to overlap to do a complete 3d image of the sample, do you know how can I do and how can I align the different stacks? Also, is there a way to count the cells in the 3d recosnstruction? Every time I try with the 3d of just one stack, the program says to “initialize” but doesn’t work at the end. Thank you have a nice day !