[Frank Verberne]

Using vizact.parallel() seemed to be the solution. Face.addAction is used because I use a custom face. For anyone interested:

#Blink morph IDs of blinking
BLINK_MORPH_LEFT = 0
BLINK_MORPH_RIGHT = 1

#Action that will animate blink closing
close_eye_left = vizact.morph(BLINK_MORPH_LEFT,1,0.1)
close_eye_right = vizact.morph(BLINK_MORPH_RIGHT,1,0.1)
closing_eyes = vizact.parallel(close_eye_left, close_eye_right)

#Action that will animate blink opening
open_eye_right = vizact.morph(BLINK_MORPH_RIGHT,0,0.1)
open_eye_left = vizact.morph(BLINK_MORPH_LEFT,0,0.1)
opening_eyes = vizact.parallel(open_eye_left, open_eye_right)

#Action that will wait 1-5 seconds
wait_blink = vizact.waittime(vizact.randfloat(1,5))

#Action that will blink indefinitely
blinkAction = vizact.sequence( wait_blink, closing_eyes, opening_eyes, viz.FOREVER )

#Add blink action to avatar
face.addAction(blinkAction,0)