Help needed from Experts. Family Visitor Visa

Hi Guys,

I have ILR and live in 1 Bedroom flat with my wife and two children.

My Sister's family wants to visit me in UK. I have to send them Invitation documents and proof that I can accommodate them here in the UK. They don't want me to sponsor them as they have strong financial statements and assets to show in their application.

The Problem is, they will be staying with me and my accommodation is very small but as they are coming only for 10 days, so we will manage as I have one Large Bedroom and I Reception which can be used as Bedroom.

The number of applicants who are intending to come here are:

My Sister and My brother in Law + their 3 Children.

The Question is whether ECO will have any problem with that or is there anything that i can do to avoid the refusal on the basis of small accommodation.

Many Thanks