How hard is to to adopt from a SLPC

I have been caring for my foster son for over 2 years and we were just told that C&Y does not have enough to do TRP and C&Y suggested SPLC. From what i understand this gives the bio parents rights to unsupervised visits and over night visits. This makes my husband and i very nervous. Both bio parents are heroin addicts.In court the bio parents agreed to do a SLPC but they made it clear that their goal is to reevaluate and fight for full custody later, once the father has served his sentence in another state for 18 months. What should we do?