Does she need shampoo, could you use a cleansing conditioner? These are better for detangling hair. Tear free shampoos are on the neutral to alkaline side which is not ideal for keeping the cuticle flat on hair, for slip or aiding detangling.

Some people also wash their little ones hair with them laid on their back on a towel, hair over the sink; otherwise there are also guards that fit around the hairline to stop bubbles getting onto the face.
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond/ fractionated coconut oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Au Naturale styling gelee
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect