My wifes sister is a 54 year old person with down syndrome.
Its getting hard to put her in my vehicle...a 2003 Nissan Pathfinder in very good condition.
Is there some way to modify the car to help?
Any other suggestions?
You need to find a mobility adaptive equipment dealer in your area and get a consultation. There are many types of vehicle modifications that can assist you.
I do not what area you live in but one place that has many resources and can recommend is a local hospital that has a rehabilitation department. The rehab specialists there can offer resources and suggestions of adaptive equipment dealers.
You can also contact the the National Mobility Equipment Dealer Association and visit their site for more info: http://www.nmeda.org/
Here is a link to the consumer area that may have answers to some of your questions: http://www.nmeda.org/consumers/consumer_guide.html