1 granny, 2 great aunts, 1 daughter & 3 grandchildren

It would be helpful to know the length of the trip and what you would be comfortable spending. "Budget" means different things to different people. How many rooms would you want to split into?

Try Booking.com (http://www.booking.com/). Use the search box to put in your exact dates. Click on "more options" in the Guests box to put in the number of adults and grand kids. Put in the ages of the GKs when the boxes come up to do that. Their ages will affect the pricing.

Click on "Additional search options" to place more filters on your search results. To get the broadest range of results at first for your very large group, I would ignore everything there except Review Score and click on Very Good 8+.

As an experiment, I did all that, chose Amsterdam City Center as the the location, kept the kids below the age of 7 and left 1 as the number of rooms. The system automatically came up with options recommended for 4 adults and 3 children. They usually were for 2 rooms. Only 15 lodgings could accomodate your group on the experimental night I chose. There may be more for the nights you plan to be there.

I always Sort by Review Score. The prices for this experiment were all over the map. That knowledge can inform you as to how much to expect and what kinds of places cost how much. The best rated by people who have actually stayed there are not always the most expensive.

Now, you need to try it on your own with the real data for your trip and group.

Thank you so much Lo. Some helpful tips there. Nancy, yes I was short on info. Some places such as hostels do offer 1 family room with 8 beds which is fine for our team. Apartments offer e.g. 3 bedrooms, sleeps 7 also fine for us. Budget for our team is around €30 per night per person. We are planning on staying in Amsterdam for 1 week in July. It is not so easy to move every couple of days with this many in the group. We thought the children would love the cycling in Amsterdam. Thanks again for your help.

Be sure to get a hotel with an elevator. Many of the canal-house places have very steep stairs and no elevator--your grannies may not be able to handle it.