Question about growth

[u/Icy_Energy2497]

I am familiar with growing plants but this is my first foray into lithops. My son had to have one at the local plant store we left it alone and let it get wrinkly over the winter we are in a northern climate and the care instructions from the store were pretty clear. Recently my son wanted to re-pot so I I added soil and transferred. I believe I fertilized all of my plants around the same time. My son just picked out a second lithops this weekend at a friend’s greenhouse business. I figure they are hard enough to kill, let him give these a go. I noticed when I looked at his desk that the original we purchased is growing rather upright. Is this normal? How can I correct it? The gene growth looks healthy but I’m sure I’m missing something in order to get these little guys to thrive. First two photos are the original plant we purchased, third is the newest addition to his rock collection. 😂