llo Maria,

One of the best approaches I know to adapt second language teaching to diversity, is "multilevel teaching".

https://www.englishclub.com/teaching-tips/teaching-multi-level-classes.htm

http://www.pearsonlongman.com/ae/download/adulted/multilevel_monograph.pdf

Although it is usally applied to students with different background and expertise, it is also very useful for kids with special needs.

http://www.cal.org/caela/esl_resources/briefs/multilevel.html

http://eric.ed.gov/?id=ED379953

A good sequence would be:

a) Needs assessment.

b) Lesson planning ( for example, with  Project-based learning. )

c) Grouping strategies and purposes. 

d) Conditions for using native languages. 

e) Using self-access materials for thematic instruction and self-assessment

Readings:

http://www.wholeschooling.net/WS/WSPress/Authentic%20MultiLvl%206-25-02.pdf

http://calicospanish.com/meet-the-needs-of-all-students-in-a-multilevel-language-classroom/

https://www.diva-portal.org/smash/get/diva2:4422/FULLTEXT01.pdf

thank you!