The main source of supply in the process of creating and updating the BDOT10k database is data from the official EGIB, GESUT, and BDOT500 databases. For this reason, the degree of harmonisation of these datasets is crucial. The study of the level of harmonisation of the EGIB, GESUT, and BDOT500 datasets with the BDOT10k database in terms of data quality and supply was performed by analysing the conceptual models of the discussed spatial data registers. The study of the degree of harmonisation of datasets was performed by classifying the analysed object classes into one of three groups, characterising the consistency of the attribute values: full, partial, and none. Analysing the degree of harmonisation of the conceptual models in terms of spatial data quality, it was found that the possibility of feeding quality properties from the EGIB, GESUT, and BDOT500 databases into BDOT10k is limited. BDOT10k has definitely richer characteristics regarding data quality. Analysing the extent of harmonisation of conceptual models in terms of feeding the data of the BDOT10k database with data from EGIB, GESUT, and BDOT500, significant inconsistencies were found. The data supply from these databases is limited especially in terms of descriptive attributes. Acquisition of geometric axes of linear and surface objects does not pose major technical problems. Potential difficulties will arise from, among others, topological and geometrical errors, such as close proximity of vertices or different segmentation. Correcting the conceptual model of the EGiB, GESUT and BDOT500 databases in order to achieve a high degree of harmonisation with the BDOT10k model is feasible. All that is needed are appropriate institutional formal and legal actions.