The increased population messages from the desktop versions were inadvertently left in the iPhone version and will be removed in a bug update. The maximum population is 40 under normal conditions, 41 or 42 with the birth of twins or triplets.
The collections are difficult to complete, and it's not likely that you will find them all in a few days. It depends somewhat upon how long and often you play, and some players have reported working on them for a couple of months before completing them all.
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Barbara
Unicorn
Last Day of Work