I worked with a mother last fall who was developmentally delayed, although
she didn't have the added challenge of a multiple birth. Some things that
seemed helpful to me:

Often women in this situation have other people working with them - social
workers, public health nurses, etc. It helps to share your breastfeeding
advice and information with them as well so that they can reinforce and
remind the mother.

Try to give information in several different ways: talk to her, draw
pictures, give her something in writing (but written in simple language, and
with diagrams), show her a video, demonstrate with a doll, let her try it
with a doll, etc. Expect to have to repeat things.

I found this mother was not likely to ask questions, so I would say things
like "sometimes mothers ask me about..." and share information I thought she
should have (for example, about nipple confusion and giving bottles). But
it's important not to overwhelm with information. One thing at a time.

Teresa