Lets add another wrinkle underneath, look now details edited exactly where its needed. 
Next, add some here, select those polys and smooth-shift them once then move them around 
There you go, bit of an angry look now. The next thing I want to do now is select those polys and spinquad them 2 time to get this result:   
Now select those vertices...and use wrinkle plugin again, result is shown below:  
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