Hi Richard, when you import the Wav file into your T4 expansion memory be sure to select 'fixed pitch'.
Doing this enables you to press ANY of the 61 keys on the keyboard to trigger the audio file of 'children laughing' to play.

Next: assign this expansion memory voice to Right1.

Now simply go into MulitPad Creator and activate 'record', press any key on the keyboard (the children laughing plays) then press stop and store this in Pad1.
Now, when you load the newly created MultiPad file and press Multi-Pad 1, the audio file of Children laughing will play.