Historically accurate to NOT have all your $$$ in one stock. Also accurate to say some stocks are better options than others but you must watch the market carefully. When AT&T was broken up into the Baby Bells, we got stock in all of them in exchange for the AT&T stock we held. Some evaluation by my better half and we decided that BellSouth was the best of the lot and went for all BellSouth. It split multiple times (2:1, 2:1 and 3:2) so it was the best choice at the time. Still have a bit of AT&T but just let it ride as it still pays $2+/share each year.
Have an in-law who worked for a bank for years and ALL the money was in the bank's stock. Nothing anyone in the family said could change that fixation of "It's bank stock! It's the best choice!" until the stock went down to 20 cents on the dollar or less. She could have gotten out on the way down but would not. Can't fix that. If you go for a single stock or a single area of the market, you must watch the market closely or possibly end up with pennies instead of dollars.
You can offer guidance but it may be ignored. I'm accustomed to being ignored - but we're in better financial shape than those folks are.