Estimating contemporary effective population size (Ne), sibship and parentage can be useful for designing and monitoring plant translocations. Contemporary Ne is an important indicator of population viability, as it considers several demographic factors, e.g. sex ratio, mate compatibility, inbreeding, nonrandom mating, and family size. Sibship and parentage analyses allow not only estimating genetic relatedness of transplants and post‐translocation generations, but also selfing rates, parent contributions to offspring and contemporary seed and pollen dispersal. Sibship assignment method was used to reconstruct offspring pedigree and parentage and to estimate contemporary Ne, selfing rate, and contemporary seed and pollen dispersal in wild (used as seed sources for translocation) and translocated populations of the self‐compatible, insect‐pollinated Dianthus deltoides (Caryophyllaceae). Source populations show very small Ne estimates (5–21) and high selfing rates (28.6–68.9%), despite high census sizes. The first post‐translocation generation (recruits and transplant seed progeny) showed small contemporary Ne estimates (19–53) and substantial selfing rates (8.4–22.3%), despite high flowering sizes, overall genetic diversity and multiple paternity. Parentage assignments revealed high levels of admixture between sources, restricted seed dispersal and successful—often restricted—pollen dispersal in the post‐translocation generation. Pollinator service, crosses between selfed or related transplants and floral display, may have contributed to selfing and pollen dispersal patterns in translocated populations. The present findings support the interest of sibship and parentage reconstruction as genetic tool for designing and monitoring plant translocations, emphasizing the importance of assessing the genetic quality of the transplants, and contributing to a more precise evaluation of population extinction risk.