First a hint:
For sims you plan to kill and then add as ghosts to your household, use one sim to befriend to max green line. Why? Because when they appear as ghosts, you can instantly invite them through a line inside friendly options.
Ghostly is pretty easy.
Kill a sim, don't destroy the urn/tombstone and don't put it in house inventory but keep it in or outside the house, wait a few days till the ghost appears (after midnight), befriend the ghost (max green line) and invite to live with you (chat option among friendlylines):
http://s29.postimg.org/y1kqj278n/ghostly.jpg
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Black Widow is also easy, although needs a lil' bit of time.
So your sim has to burry 5 spouses. Okay. Marry then kill one by one. Aging on/off is irrelevant, the fastest way is to marry 5 elders or ageup spouses on the cake instantly to elder then double woohoo in the rocket. Why not anger kill? Because after marriage spouses will be so happy it's nearly impossible to get them angry. And why not laughter kill? Because it's more timeconsuming than woohoo with elder sims. Not saying you shouldn't try that:
http://s13.postimg.org/e5qtiac6f/blackwid.jpg
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What Would It Be Like is - bugged.
Still achievable though. It will not trigger if your sim woohooed ghost sim before becoming ghost!
Means what? If you'll do it with one of exes that are now ghosts from previous achievement, the living spouse can't get the achievement. Use another living sim to woohoo one of those dead spouses!
The achievement text should say "woohoo with a ghost sim for the first time".
http://s7.postimg.org/khk09m8yz/wooh.jpg
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Like woohooing achievement, the text description for Ghost Family is not really true.
You definetly have to put 8 ghosts in one house and then play that house.
But those ghosts don't have to be a family of mothers, fathers, brothers, sisters, etc. They can be nonrelated. And it's good that it's made like that because many players have glitches with ingame relationships currently.
In any case you'll shuffle sims through manage household option till you get 8 of them, then you'll put all 8 in one house and start playing that house. The achievement will kick in and next you'll do is kicking those annoying ghosts, at least a few of them, out!
http://s4.postimg.org/x9umv9hvx/family1.jpghttp://s28.postimg.org/wa98486ml/family2.jpg
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Next one to pursue although I said I won't go slotmachhine as I hate gambling, is tripleplay. Wish me luck.