How do you become a mermaid? Is there an easy way?

[ScarlettMidnight]

From my understanding it's a lifetime happiness reward but I've also heard if you make friends with one = they can give you kelp to turn you. I've noticed you can buy kelp from the grocery shop, if eaten by a human sim what would happen? 

I'm really, really want mermaid sims but there's got be an easier way than waiting for life points to build up or achieving the lifetime wish.

I've tried making friends with a mermaid that I got from exchange but although it worked an option for "ask to be turned" did not appear nor did a "give me kelp" option. So my guess is it only works with in game NPC mermaids or it isn't true.

[Tixxis]

Welcome, ScarlettMidnight

Nothing will happen if you eat kelp from the grocery store. What you need is Mermadic Kelp. It can be bought as a Lifetime Wish Reward for 25K.
The other way to get it is by befriending a mermaid. Underwater it's difficult to build friendships. Try to get to know one and build up your relationship on land.
Then, when good friends or better, go diving together and ask the mermaid about her/his 'fish parts' (underwater). The mermaid will give you the special kelp you want. Eating it can fail and make your Sim ill, but it you have a real good friend relationship with the 'donor' this should not happen. You'll become a mermaid.