To validate the quality of software, test cases are used. These test cases are often manually-written, which is labor-intensive. To avoid this problem, automated software testing was invented. Search-based software testing is a useful tool for developers to automatically generate test cases. However, improvements are still needed to create test cases that compete with manually-written ones. EvoMaster is a tool that generates system-level test cases for RESTful APIs using the MIO algorithm. An important aspect of this algorithm is sampling new test cases. Currently, EvoMaster employs random and smart sampling to achieve this goal. This paper aims to improve the coverage of the generated tests by expanding the sampling methods with seeded sampling. This method consists of extracting sequences of HTTP requests from manually-written tests and using these to sample new test cases. Seeded sampling is evaluated on two RESTful APIs with 7 different parameter sets. We show that the addition of seeded sampling can improve the coverage achieved by EvoMaster compared to the current combination of sampling techniques. Nonetheless, this paper has some limitations. It only takes two RESTful APIs into account and has a small amount of benchmark runs to back its findings.