From the baby spoons, Lisa holds 4 children * 3 spoons each = <<4*3=12>>12 baby spoons.
Adding this to the decorative spoons means Lisa has 12 baby spoons + 2 decorative spoons = <<12+2=14>>14 old spoons.
In the new set of cutlery, there is a total of 10 large spoons + 15 teaspoons = <<10+15=25>>25 new spoons.
So in total, Lisa has 14 old spoons + 25 new spoons = <<14+25=39>>39 spoons.
#### 39