Babies and Photography

My experience with photography & babies is limited.  I have some very cute pictures of babies, but they are not posed and squished into a special sack.  Last Sunday I tried VERY hard to do just that with my grandson Louie.  The room was set with five layers of blankets on a bed (used as our poser),with a nice wedge in the middle for baby posing and a portable heater to keep the room warm.

 The wedge is there!  How exactly does the baby lay in it again?  Not happening.  Oooops no diaper..three layers of blankets suddenly wet.  So now what to do?