In a previous SAXS experiment at Max-Lab (Sweden) we observed that the thermotropic mesophase transitional behaviour of the monoolein(MO):cholesterol:water system was significantly perturbed, when silica nanoparticles (SiO2 NPs) were added (cf. Fig. 2). However, the spatial distribution of the NPs in the mesophase and their aggregation behavior within the mesophase remained unclear. Here we propose a SANS study at SANS2D, using the same monoolein:cholesterol mixed samples, with the following goals: 1) high resolution mesophase determination of the system invaded with silica NPs, and 2) simultaneous determination of the spatial distribution and organization of NPs within the mesophase by contrast matching. In doing so, we will systematically vary the NP size and the NP volume fraction. Our results will provide mechanistic insight for such peculiar mesophase behavior of lipid-NP mixtures.